[G Pad 8.3 Q&A, Help & Troubleshooting] DarkSunLtd:
Hello to all! Thank you for taking the time to read my post and questions!

While I'm quite PC savvy, I've never had the extra funds to invest in mobile devices such as tablets, but as luck would have it a buddy found a handful of old G Pad 8.3 (aka LG V510) tablets at a local dump early last year and dropped them off to me to play with. I successfully unlocked and rooted them all and was able to use the LG Flash tool to flash the proper 4.4.4 stock ROM to them, as well as using the mobile support tool (which is now defunct) at one point in mid 2021 to do updates from LG itself.

Not long after getting the tablets running I became sidetracked with other must do projects for months and these tablets languished here. Recently I pulled them back out, as I have more time to investigate uses for them at present.

The first tablet I moded allowed me to run Ubuntu and log into it from my desktop with VNC. No problems there. I can even install my mail server on it now that Linux is more exposed.

The next tablet I tried to mod I accidentally flashed the wrong firmware to... Bricked..... No power, no noise, no vibrate. All that I can see for any sort of response from the tablet is seeing Quallcomms 9008 mode in the Windows device manager, or Qualcomm, Inc. Gobi Wireless Modem (QDL mode) in Linux. Holding the power button for 15 secs will make the port reset but it doesn't change in any other way. the CPU is running as it stays warm until I disconnect the battery.

I have spent over 2 months trying to resolve this issue, using both Windows 7 & 10, as well as Linux, and so far no luck. I've downloaded MANY gigs of files. With Qfil and other similar tools, its constant sahara errors or firehose errors, despite having what appears to be the proper files for the firehose. The LG Flash tool tries to read it but then says the device is "differente", giving an F0000002 error, so I'd presume the wrong firmware flashed caused a change to the version number somewhere... So now the proper version won't flash with that tool...

On Linux, the only halfway encouraging responses I get is using a tool called EMMC_Recover. That tool on Linux has allowed me to send some partitions to the bricked device over USB, but certain partitions such as boot.bin, and a couple other needed partitions, EMMC_Recover responds back with a 256 error, which is an I/O error, so I would assume something is locked or not rooted proper any more on the bricked device after flashing the wrong firmware?

I have a good copy of a backup of one of the working tablets with stock ROM at 4.4.4, but have not been successful in getting the files all back onto the bricked device so it will boot.

I have also tried booting from an SD card, setting the card up a few diff ways as instructed online, but it made no difference. Button combinations combined with battery disconnects and reconnects while connecting the USB cable seem to make zero difference in its behavior. it's just plain dead other than the few things I could do with EMMC_Recover.

Other things I have tried included making up a 910k cable, which made no noticeable difference. Shorting the D+ to GND, no difference. Making sure the battery was fully charged on a working tablet, since it will not charged on a bricked tablet, but again no difference.

I realize that some devices have test points that need to be jumpered to flash them but where the device is already in 9008 mode I dont see the need, nor could I find any info what so ever about test points on the G Pad 8.3. The most I could find is a boot config setting in the service manual for this device, but the points are unclear in that manual and would take some time to trace out, if even possible short of removing the CPU/EMMC from the mother board.

I also read last night that while these devices can show as 9008 mode, that sometimes its not fully in that mode, but I cant confirm that myself. Does anyone know for sure?

JTAG sounds like its been an option for some bricked devices, but I dont have funds to risk on buying a box that may or may not work. The JTAG port pads are exposed on the edge of the board with no connector soldered on, but the chances of getting wires soldered onto that spot effectively and have the pads not tear away from the board are slim.

I'm also not sure what software would be used if I was to make my own JTAG device using something like a Pro-Micro ATMEL device. The JTAG hardware can be made, but I dont have the knowledge needed as to what to flash and where and how, and an extensive search really didn't answer those questions...

I'm not usually one to bother others with hardware or software issues, as I can usually work it out myself over enough time, but I seem to of run out of viable options after a couple hundred hrs of extensive reading and trial and error, so I am hoping someone here might have some other suggestions to try. Any help would be greatly appreciated.

Thanks to all for what you all do to help many people in need each and every day here! :)