NVFlash for Dummies

OLD ARTICLE – Probably has errors

Installing ClockworkMod Touch & Stock Bootloader (1.2)

This guide was last updated 07/03/2012 by Ray 

Visit the NEW version of this guide if you want to install Jelly Bean (Android 4.1) on the GTab.

See my video instructions at the bottom of this article.

ClockworkMod Touch

NEW ClockworkMod Touch on gTab


The NVFlash tool (program) is the PRIMARY Starting Point for any major changes or software fixes to your GTab. If you are having ANY problems with your ViewSonic G-Tablet, this is THE guide to follow.

NVFlash – also called “APX mode” can be used for several essential functions. Regardless of your previous configuration, by using this guide, you should be able to perform the following operations:

  • Regain control of your GTab after it is “bricked” or otherwise unresponsive (stuck in a loop at the “3 birds” or some other screen, etc). See Note1 (below) if you continue to experience loops even after flashing with this version of NVFlash.
  • Increase the size of the system partition from 200Meg (stock) to 250Meg (this may explain some failed ROM flashes.)

Note1: Some of the newer ICS ROMs may be too large for your gTab even with a 250MB system partition (due to hardware issues on SOME gTabs). If you experience consistent boot loops when flashing a new ICS ROM to your gTab… TeamDRH has created another version of their great NVFlash package that will expand the system partition to 300MB. I do not recommend that you use it unless you are having problems. Still, click HERE to download that package. Use is exactly the same as the one we link below.

  • Return your GTab to a STOCK configuration with the 1.2-4349 Tap-n-Tap. (Recovery is NOT stock.)
  • Change the bootloader version on your GTab from (old) 1.1bl to (new) 1.2bl. Note here that – for current ICS ROMs – the bootloader version is NOT significant. You can use new ICS ROMs on either bl. BUT, the system partition must still be expanded. So, we recommend that you use our 250MB NVFlash which will also convert to 1.2bl.


  • This process will likely void your warranty.
  • Assume that EVERYTHING on the GTab will be erased or deleted. However, that is not entirely true. NVFlash cannot erase anything on the SDCard (see this post). STILL, anything can happen.
  • Any use of this guide (or anything on this website) is done SOLELY AT YOUR OWN RISK!

Neither Ray Waldo, this website, its owners, or operators take any responsibility for your actions related to the use of any article/guide on this site. You have been warned. 

DOWNLOAD OUR FILES. Even if you have used NVFlash before and already have it installed on your computer,  USE OUR VERSION instead:

DOWNLOAD: NVFlash with Stock ROM & CWMR Touch 5504  at the TeamDRH site here (or from us here.) This archive includes all the files that you will need (for both Windows & Linux) to install NVFlash and complete this guide. This guide will install both the Stock T-n-T operating system and the ClockWorkMod Recovery.


Using NVFlash:

Note: There are two modes of operation controlled by booting with the volume buttons:

  • You get into APX mode by pressing the power and MINUS button. The gTab will flash on then go black. When in that mode, the GTab appears dead but will respond to commands from the attached computer – using NVFlash. If you mistakenly get into APX mode, just hold the power button down for about 30 secs to power off and exit the APX mode.
  • You get into RECOVERY mode by pressing the power and PLUS button. When in that mode, the GTab has a menu of options to allow you to flash an update, reset to factory, etc. No USB connection or computer is needed to use Recovery. To get out of Recovery mode, always click on the “Reboot to SYSTEM.”


If you have already successfully used this (NEW) guide, then you can skip to the PROCESS section.

  1. Backup any data on the GTab that you wish to save and copy it to some external storage. These procedures potentially delete everything on your GTab.
  2. Charge the battery to at least 70%. It is also a good idea to leave the power cable connected during these operations.
  3. Power off the GTab & remove your external SDCard (if you have one in the device).
  4. Download the NVFlash file from above.
  5. Extract the archive and rename the extracted folder to nvflash.
  6. LINUX ONLY:  You must make the nvflash file executable – Open the nvflash folder; right-click on the nvflash file; Properties; Permissions tab; Tic the box to run the file as a program. Then  Skip to the “PROCESS” steps below.
  7. WINDOWS ONLY:  INSTALL the APX drivers located in the “Flash USB driver” folder.
  • On the GTab, hold the Volume minus (“-“) button AND the power button until the GTab comes on and then goes BLACK (this is the APX mode
  • CONNECT the USB cable between the GTab and your computer.
  • When the gTablet is detected by Windows, and you are prompted for drivers, point the wizard to the ‘Flash USB Driver’ folder (inside the new “nvflash” folder.
  • The driver install should complete normally and you will hear an audible connection sound.
  • Power off gTablet by pressing the Power button for ~5 seconds. 


Do not connect the USB cable to the GTab unless instructed to do so. Also, be sure to DISCONNECT the USB cable when the guide says to do so.

  1. WINDOWS ONLY: If you have not installed the APX/USB drivers, then go back to the “PREREQUISITES.” Step and complete this step first.
  2. On the GTab, hold the Volume minus (“-“) button AND the power button until the GTab comes on and then goes BLACK (this is the APX mode).
  3. Connect the USB cable between the GTab and your computer. (If you continued from the previous section, the cable may already be connected.)
  4. On your computer, open a COMMAND PROMPT (or terminal), CD (change directory) to the nvflash folder & run the NVFlash program: Windows users, run the nvflash_gtablet.bat —  Linux users, enter the command, “sudo sh ./nvflash_gtablet.sh (without the quotes. – note the space after the “sh” and before the “./nvflash” characters.)
  5. Wait. The NVFlash tool will only take about two minutes to complete. Do not proceed until it reports that it is finished.
  6. Turn the GTab off by holding the power button until the line of text at the top of the screen disappears.
  7. Remove the USB cable (You are finished with the computer. Everything else is on the gTab.)

Partition the SDCard

From user Steve T.: The new CWM uses different navigation buttons than the previous version and now even has soft buttons at the bottom of the screen which makes it much nicer. The big difference I saw was that the ‘home’ button on the right side is now the UP arrow and the ‘menu’ button below the ‘home’ button is now the DOWN arrow. I think the select button is now the ‘search’ (magnifying glass) button.

  1. On the GTab, start ClockWorkMod (CWM) RECOVERY: Hold the power and volume plus (“+”) buttons until the “recovery key detected” text appears at the top of the screen.
  2. Select “advanced” and press the Home/Enter button (arrow on the right side of the screen).
  3. Select “Partition Internal SD Card” and press Home.
  4. Select “4096M” and press Home – then select “0M” and press Home again. The GTab will report that it is “Partitioning Internal SD Card.” Do not touch the device until it reports “Done!” at the bottom of the screen.
  5. Repeat steps 3 & 4 but select “2048M” & “0M” (rather than 4096M & 0M).
  6. Select “+++Go Back+++” and press Home.
  7. Select “power off” and press Home.

Reboot into Stock

At this point, you will have the stock Tap-n-Tap operating system installed. It is a good idea to fully boot into T-N-T and assure that it is working before proceeding to flash a new ROM.

If you wish to flash a new custom operating system, here is our list of viable candidates: ROMs for the GTab

Video Instructions for NVFlash & Installing ICS


To determine if your device has the LARGER system partition…

(if you did this NVFlash, then it DOES.)

To check the size of your SYSTEM partition, open the Terminal Emulator app (free on Play Store), enter “df” (without quotes). The “Filesystem” area is at the top of the list (either turn the GTab to portrait mode or scroll up to view the top of the list). Check the line that ends “/system”.

My device (with 250meg system) reads:           /dev/block/mtdblock3 253696 216480 37216 85% /system

If your device shows something around 200000 instead of the 253696, then you probably have the smaller (200meg) system partition.


TELL US about your experience in the comments below.




Tagged , . Bookmark the permalink.

266 Responses to NVFlash for Dummies

  1. John says:

    Please ignore my question about Linux recognising the Gtab in APX mode. I tried a few more times and it just worked (don’t know why).

  2. John says:

    Hi Ray,
    Thank you for the great article. I am a new Linux user (and I’m trying to fix my Gtab). I have a laptop with Vista on it and it recognises the Gtab in APX mode, but I can’t get my Linux Mint laptop to recognise that the the Gtab is plugged in (this is only a problem in APX mode). Is there something special I have to do in Linux to get the Gtab to be seen when it’s in APX mode?

  3. Matthew Gallas says:

    Hey Ray! So I scanned through all the comments on this page and I don’t think you’ve addressed this problem yet. I followed your instructions for installing ICS to no avail (kept getting stuck at 3 birds) so I went ahead and ran the nvflash with the 300mb system partition and got JB loaded up. Everything was going along swimmingly and I was updating and downloading some apps. However, at some point, the tablet went to “sleep”. Now I’ve been messing with the gTab for a year or two now and I’ve experience SOD before but this is like… permanent SOD or something. The tablet won’t turn on at all. Won’t boot into APX, won’t boot into recovery, won’t boot into anything. I get the indicator light when I plug in the power cable, but other than that, it seems like it’s just dead. Any ideas how to proceed?

    • Ray says:

      Pop the back off and hit the reset button.

      • Matthew Gallas says:

        Ah, I was afraid you were going to say that…

      • Matthew Gallas says:

        Well, did the internal hard reset and it booted back into JB but every time the screen turned off, it did the same lock-up/dead tablet issue and I have to hit the button again. That happened 2 or 3 times, but now on the last hard reset I’m stuck at 3 birds. I’m about to just chuck this thing in the trash!

        • Ray says:

          Sounds like you have an error in the flash. Repeat the NVFlash using a smaller system size.
          To tell you the truth, you can spend $200 on the Nexus 7 and have a FANTASTIC tablet and you will never turn the GTab back on – unless it is to show it to a potential buyer (grin).

  4. I have installed different roms on my gTab and am not new to this. However, I recently upgraded my Windows desktop to Win 8 and since then I am unable to install the APX drivers. Is there something I am missing? The device just refuses to install…..Any help appreciated!!!! Thanks in advance!

    • Ray says:

      Yeah, I dislike Windows also! That is why I use Linux.
      Only suggestion is to connect the gtab, in device manager delete any drivers with “?” or “!” or say anything about the Android or tablet.
      Disconnect the gtab and reboot.
      Then set up nvflash completely new – even a new folder.
      When you connect the gtab, FORCE Windows to use the drivers in nvflash.

  5. I was working with Vegantab with bl 1.1 with no probs, but then I tried to install full stock touch and the gtablet wont boot anymore, only on APX. tried to install full stock 300mb, old roms such as cwm or old nvflash stock 1.1 rom, it goes all the way until tapntap logo but then it boots loops. When I turn off the gtablet just enters into APX no matter what rom I load. Im really stuck and don´t know what to do. please help! I wanna see the birds again!

  6. Ray, thanks for assisting, Merry Christmas and Happy New Year to you too! I have tried both of your packages and get the same error, regardless of what I nvflash to it (have tried numerous other d/l’s as well) : sending file: “system.img 131072/125207808 bytes sentdata send failed NvError 0x120002 command failure: create failed (bad data)”. It seems to always end with the (bad data) trying to send the system.img file. What next?

    • Also, just so you know, I never see anything ion the screen anymore, no birds, no recovery options, nothing, the only way I know its ready for APX is I leave the device manager open and can see it come and go as I press vol – and power. It seems APX is all I got……

    • FYI…as hope for others, I spent the last 2 days messing with this. Turns out my perfectly good looking usb cable was bad….dohhhhhhhh…..oh well. it was fun….

  7. Hello, I have no idea what I did, but I am stuck in APX mode only, nothing else will come up, no birds, no recovery menu. I can run all of the nvflash files, but no matter what I run it winds up with “sentdata send failed NvError 0x120002” on the system.img file. It was 1.1bl, went to 1.2bl, somewhere I messed it up. Any ideas? thanks…

    • Ray says:

      It may be that you used the larger (350MB) system partition and that your device will not support it (some evidently don’t). Start over with the 250MB version (see my links) and see if that works.
      As long as you have APX working, you are not broken. If it truly gets STUCK in APX, just hold the power button until it powers off. Leave it for a while and then power on normally and see what happens.
      Merry Christmas!

  8. Luigi Stellon says:

    I have a viewsonic g tablet (1.2) a couple of weeks ago i installed nvflsh with CWM since then it is stuck in APX mode I surched forums with what seem to be the same problem i was having. i tried drainning the battery, removed back cover and made a reset. Tried at different times to nvflsh with CWM and using specific part.img and when i am able to reboot in Viewsonic stock i never see the 3 birds it starts with the g tablet logo. I just finish trying with your post “NVFlash for Dummies” and same result everything is ok until i get to the part (1) to start ClockWorkMod Recovery by holding the power button and volume plus and that is where my problem it won’t go on to CWM recovery.
    Please help
    Let me know if you need any additional information

    • Ray says:

      When you changed the partitions you probably got something messed up. I do not have any answers for such engineering issues. Sorry. Next time, come here BEFORE rather than after you do those unsupported things.

  9. Ima Bricker says:

    Hi Ray,

    Installed the latest JB from where you recommended today(TeamDRH-JB-Alpha-5.3.zip). My 10 year old was playing a trivia game and the screen went blank. No amount of pushing the power button would make it come back to life. I pushed the power button by itself varying amounts of time from 5 seconds up to 1 minute in 5 second intervals. I also tried pressing & holding the volume – button, then pressing and holding the power button. Nothing. Tried holding the – button, then hold the + button, then press and hold the power button. Nothing.
    I plugged the gtablet into the PC that I used to do the update and it starts to install a driver: MTP USB Device. It loads, but fails to install. The PC sees that something is out there, but is unable to connect.

    Right now I’m bricked with a frowning 10 year old. I seem to remember a post a while back on drilling a hole to get at a reset button…

    Any ideas on how to bring this thing back?

    • Ray says:

      First of all, you evidently failed to read the disclaimer at the beginning of this post that says this is NOT the newest or recommended version!
      It should not be necessary to drill a hole (but many people have done so). I have never needed to do anything but hold the power button consistently for about a minute. If you do need to do more, just open the back and remove the battery connector for a minute or so.
      For all further questions, please post your comments on the page with the article that is related to your issue (in this case, you should have posted on the article where you found the ROM that you flashed.

      • Ima Bricker says:

        Remove the back? I can’t see any screw holes or obvious tabs. Is there a place to get this info? As it is, I think I might just see if over night will kill the battery and I can then maybe boot. I will keep the rest of my comments in the 5.3 version page until I have the CM10 (Smoother) ROM working and then I’ll move to that page. I’m a quick learner 😉

        • Ray says:

          Remove the rubber “feet” and the 4 screws underneath. Then use a knife or credit card to separate the edges and the back wall pop off.

          • Ima Bricker says:

            I found the info at youtube. I should put a link here, but I’m not sure how. I have a beautiful “carbon fiber” cover on the back that I would have to cut holes in. I let it go all night, and it still had enough juice to make my PC want to install the MTP USB Device drivers. So now I have an old USB LED lamp plugged into to it. When it goes dark (it has been 3 hours already!) I will know the battery has finally died and I can plug it in to start the reboot! I will let it charge for a few hours so that it doesn’t run out of juice as I’m taking it back to stock. This will be the last post here, I will update the other thread when I can get it to reset. Thanks again.

  10. Timothy says:

    Hi Ray,
    I had issue with nexus 7 and when searching web for solution founded this video and that guide.
    Unfortunately it’s for gtab 🙁 and i had a different situation.
    I was on bootloader 3.14 (stock 4.1 rom, trinity kernel) and then when android 4.2 i’ve tried to flash my bootloader with wub fresh nexus root toolkit. Seems like it flashed by then I can’t boot up. Google logo appears and then disappears for many times. I managed to get into APX mode. But nvflash doesn’t work for me. (tried to run on both – windows and linux) – after any nvflash command it returns message “Unknown device found” . [Linux see device because when I write lsusb at terminal it returns list of devices including 0955:7330 Nvidia Corp. device. ]

    So, could you please tell me how could I flash back to 3.14 bootloader via nvflash or any other advice how could I return nexus 7 back to life?

  11. Deo says:

    Thank you for all your help. This is a lifesaver for the Gtablet.
    The NVflash went great. After the update it is asking to install the newest over the air update (V1.2-5699), I tried it and it errors out:

    Finding update package…
    Opening update package…
    E: signature verification failed
    Installation aborted.

    Do I need it?
    Any ideas?

    Thank you.

    • Ray says:

      Not unless you do not want a custom rom (you DO want a new rom, don’t you?).
      Just ignore it and continue with flashing a new custom rom and enjoy the device as an ANDROID tablet – instead of the dumb tap-n-tap os.
      Actually, if you want the newest (Jelly Bean) rom, you will need to redo the nvflash using the files associated with that ROM. The process is the same but you will replace the NVFlash files with a different set. and run it again. Once you have done it, you know how easy it is.

  12. AK says:

    Hi Ray,
    I was on BL 1.1 and did NVFlash using your process. I then tried to install Calkulin+Clemsyn version 8 from XDA. Everything happened normally.
    But when I did a system reboot after installation, the ROM just would not load. I got the “Nvidia Tegra II” screen and thereafter the screen was lit, but blank for a long time. Is this normal? What have I done wrong? Please help me out.


    • Ray Waldo says:

      You have to match the nvflash to the rom/kernel or you may have problems.
      Since I do not support that rom, I can only suggest that you either check xda for help or follow our guide and install jb.
      In most cases, nvflash will clear the hang or boot loop.

  13. Kelly says:

    Hi Ray, with all the talk about Jelly Bean, I decided to finally try ICS first. But I’ve hit a snag from the beginning. I got to Step 7 of the Prerequesites above, went into the “Flash USB folder” and didn’t find anything about APX drivers. Here is what I found: two folders named “amd64” and “i386” and two set up info files named “android_winusb” and “NvidiaUSB.”

    • Kelly says:

      Nevermind, I just realized my mistake. Read this part over and over and just now realized that I was interpreting the step incorrectly. Just waiting for my GTab to charge and then will flash.

  14. Mike says:

    I have tried to do the above and the gtab does nothing when i connect to the computer after going into the apx mode. I tried to get it to load the nvflash before but it would not work and then i had to stop the process now the computer will not recognise the tablet in apx mode . What now Gtab is still working fine but computer can not see it in apx mode so i can not load the nvflash files

    • Ray Waldo says:

      You are almost certainly using Windows, correct? That is the problem. Windows has trashed your USB drivers and installed conflicting drivers. I don’t like Windows and don’t really support it.
      However, the process is to delete all of the offending drivers (in Device Manager) and then re-install the drivers from NVFlash.
      Or, (better) install Ubuntu Linux and forget about driver problems. 😉 Seriously, check my article on building a Ubuntu thumbdrive. You can use that to run Ubuntu on your Windows machine – without having to modify anything in Windows.

      • Mike H says:

        You are amazing thanks for the prompt reply I have managed to use a windows 7 machine and went into looking for devices found it and then navigated through to install new drivers done that stage now going through the other instructions thanks for you great work. I was using my XP but looks like much easier on windows 7.

  15. Bill Stricklin says:

    I am running Linux Mint on my home computer. The software is a very recent acquisition, so I am very much a newbie. My gTablet has been “bricked” for months now and I have searched for some solution. I had an earlier version of the Android OS running but decided to upgrade to ICS. I used an app, I believe it was called Program Manager, to install the new OS and then calamity ensued. I’ve been trying the solution you have outlined using the terminal command ‘sudo sh ./nvflash_gtablet.sh’ and keep getting the message ‘sudo: ./nvflash: command not found’. All of the NVFlash file has been extracted into a folder named ‘nvflash’; all of the files within the ‘nvflash’ folder appear to be viable. Do you see anything awry in my process? Sure would like to see the tablet doing more than a paperweight!

    • Ray Waldo says:

      Sounds like you failed to do #6 in the prequisites:

      LINUX ONLY: You must make the nvflash file executable – Open the nvflash folder; right-click on the nvflash file; Properties; Permissions tab; Tic the box to run the file as a program. Then – Skip to the “PROCESS” steps below.

      You should have no problem once you do that. BTW, the app that you used is probably ROM MANAGER. It works for some devices but it KILLS the gTablet. NEVER try it again on your gtab.

Leave a Reply