This is for all the people who managed to softbrick (or hardbrick) their Lenovo Tab 3 8' (TB3-850F) tablets!
All you will need link, at the end of the post. I don't know for how long it will be up, but you can use it for now.
By the way.... Should you find something useful here... please hit the thanks button in the end
a. stock rom for the TB3-850F (Google is you friend )
b. Sp Flashtool (you can download from their official site). From there, also download the MediaTek USB VCOM drivers and Driver Auto Installer v1.1236.00 (or any latest version).
1. Install the windows drivers you downloaded
Note : If you encounter problems installing Windows drivers in Windows 10, google how to install unsigned drivers in Win10
2. Open the folder you extracted SP Flashtool and run it as administrator.
3. Unzip the rom file you downloaded.
4. Inside the folder of your unzipped rom file, look for a file similar to XXXXXXXXXX_scatter_file.txt
5. Load this in the SP Flashtool (click downlad tab, then scatter loading, load this file in there. It should load your rom you will see some colours, etc...
The tricky part:
Assuming you have correctly installed the drivers:
1. turn off the device (well if bricked it is turned off all ready) just make sure, and in SP Flashtool click options and 'with battery'.
2. Click the green download button on SP Flashtool.
3. Hold down the Vol down key on your device and connect it to a usb port.
4. If you see a red line and continue to yellow, all is probably good! Don't let go of the vol - button until yellow line reaches 100%
B. Root and TWRP recovery
a. platform tools (adb and fastboot)
b. a twrp.img (image file) for the lenovo TB3-850F copied to external SD Card and platform tools folder (google is... useful )
c. latest supersu.zip (flashable) copied to an external SD CARD
1. Grab tablet, go to settings ---> about tablet ---> click version number 7 times to enable developer options
2. From settings again click developer options and enable OEM Unlocking and usb debugging
3. Navigate in the platform tools folder. While holding SHIFT right click and select open commandline here (or similar)
4. Connect tablet to PC and in the command line issue: adb devices
If a weird number shows up and says device on the left you are all good to continue.
5. Now on the command prompt again issue: adb reboot bootloader
Your tablet should now reboot to fastboot (big Android, laying down)
6. Issue command: fastboot oem unlock (also check tablet screen for confirmation)
Wait a little bit and reboot your tablet. (should work with holding the power key down for a little longer than 10 seconds. If not hold down volume key and power button for the same amount of time - tested and working)
**At this point it is ESSENTIAL to leave the tablet to fully boot. The bootloader unlock triggers a FACTORY RESET which you must leave to complete and set up your tablet from the beginning.
** It is also ESSENTIAL to complete the boot and set up cycle because, after the automatic factory reset you will need to RE-ENABLE developer options and usb debugging. Once you are done continue to 7.
7. In the platform tools folder copy the twrp.img (you should have downloaded earlier, check upwards... )
8. Open the command line again and type:
a. adb reboot bootloader
b. fastboot boot twrp.img
** This will load up TWRP recovery only for this boot time.
****BE EXTRA CAUTIUS TO -NOT- ALLOW twrp to make modifications. Essential! Should you do otherwise go back to how to unbrick your tablet.
9. Choose install, and install supersu.zip.
10. Choose reboot to system and allow complete boot cycle! Essential!
11. Your tablet should now be rooted. However to succesfully flash the twrp recovery you need to have Busybox installed. Download as .apk and install it (at the time of writing this I believe Busybox 54 is the latest version).
12. Once installed back to the windows terminal and issue:
a. adb reboot bootloader
b. fastboot boot twrp.img
ONCE AGAIN - DO -NOT- ALLOW twrp to make modifications!!!!!
13. From you external SD Card install twrp.img, select recovery when prompted.
14. Reboot to system and enjoy!!!!
Note : Install an app that makes it easy to boot to recovery. (I personally use root essentials - Trying the combination keys did nothing for me, or just poped up the chinese options menu. That does not mean the recovery has not been installed correctly. Booting to recovery from rootessential menu, boots straight to twrp)
All you will need and credits:
(thanks button, thanks button, thanks button!!! )
Results: (it is in Greek, but you get the idea )
Hope I have helped! Happy playing with the commands and whole process!
Lastly, if you get stuck at any point, you can either use this thread or PM me for further advice, explanation and/or any kind of assistance.
Note: Special thanks to @ for actually taking the time to further help people on this thread, as unfortunately I do not currently have the time to do so myself. It is worth checking out @ 's threads also. There, you can find very useful and updated information.