[Android Q&A, Help & Troubleshooting] schrdlu:
Hello,

Think it may help : I successfully unbricked my Teclast X89 Kindow. I had played too much with the parameters of the chipset in the BIOS while trying to solve the battery drain I have with it both in Android and Windows (by the way, I reinstalled a fresh Windows 10 from standard media ; all the drivers are available from Windows Update - just need a hub, ethernet and usb keyboard for the duration of the install ; the only missing part is the configuration of the touch driver which is done by copying %systemroot%\system32\drivers\SileadTouch.fw from original install to the new one).

Anyway, the tablet didn't boot. Didn't even light up. A brick. So I proceeded to dismantle it, and find out if I could try to salvage it (which I did:)).

Find bellow my notes on the process.

HW Tools :

- EZP_XPro usb flash writer

- SOIC 8 Pin adapter cable

Software tools :

- EZP XPro software (easier to install under W7 that W10)

- UEFITool 0.21.5 or MMTool 5.00.0007 (I used that one, but it is also feasible with UEFITool ; tested it)

First thing is to dump the BIOS from the flash chip in the tablet.

Opening the tablet :

- don't forget to remove the micro sd card

- insert a fingernail (or better a guitar pick) between the black plastic around the screen and the white back and pry open gently

- follow on all around the screen and remove the cover

Exposing the flash chip :

- there is a metal cover over the CPU, partially exposing the flash chip, but not enough to position the SOIC adapter

- reposition the adhesive tape that may be holding the metallic cover

- remove the metallic cover

Dumping the BIOS :

- fix the SOIC adapter on to the flash chop (pin no 1 is upper left)

- plug the other end of the adapter on the lower 8 pins of the EZP Xpro (pin 1 is on the left)

- run EZP XPro software on your PC

- plug the EZP XPro USB cable to your PC

- the EZP XPro and the flash chip should be recognized by the software

- read the content of the flash and save it to a file

There you are. Equipped with a file that contains the EFI BIOS itself, it's parameters, internal drivers, etc. And no idea what to do to reset the BIOS parms. That one took me some time to find out how to do it somewhat cleanly.

First approach was to try to find the Setup area in the image and clear it by hand. No success that way. Then I searched for tools that could do the job automatically. No success either.

On my way through this investigations, I learned a few things :

- BIOS is from AMI, more specifically Aptio V

- there are tools to manipulate such a BIOS, mostly to replace low level drivers, microcode, etc. ; The one from AMI is MMTool ; an opensource alternative is UEFITool ; both allow to load a BIOS dump, and add / remove / replace modules or blocks of data, then generate a new BIOS image that could be flashed.

I then combined both methods (hex view the DUMP and MMtool) :

- I searched where in the BIOS I could find strings (ASCII) like Setup, StdDefaults, etc.

- StdDefaults proved to be a good marker for the BIOS configuration area (equivalent to the NVRAM in other / former motherboards)

- More specifically, I found it in the BIOS dump at two places : 0x0077006b, 0x00788069

- I then used MMTool to "create a report"

- and looking through that report, affected those two occurrences of StdDefaults to specific areas of the BIOS file

- The two occurrences were in BIOS Volumes 6 and 7 which were both of the same size and constituted by raw data.

Making the assumption that one occurrence was the default configuration, and the other the applied configuration I then proceeded to modify the BIOS with MMTool :

- intent is to copy block 6 to block 7

- in MMTool, go to Extract, then select volume 6, index 0 ; enter a file name, and press Extract button

- then go to Replace, select the file created above, select volume 7, index 0, and press Replace button

- save image as a new file

There it is : you have your BIOS reconfigured from its default configuration.

The last step was easy :

- in EZP XPro tool, load the modified BIOS image

- press "Auto" button (or successively erase, write, verify)

- unplug everything

- reassemble the tablet (don’t forget the metallic cache over the CPU)

- put it in charge and when possible, boot it

That's it.

The process should be reusable with other BIOSes.

And if someone finds out how to resolve the battery drain of the x89, I'm interested.