[Thinkpad Tablet General] Neo0:
How to unlock, nandroid and reflash Lenovo Yoga Tab 3. I tested it using my Tab 3 10 (X50F). It isn't guaranteed that it will work on other models, too. Do it at your own risk!

Files needed:

Firmware package:

https://www.androidfilehost.com/?fid=24369303960683181 [Thanks to [MENTION=997923]ionioni[/MENTION], credits to Lenovo-forums.ru]

TWRP.img: http://www106.zippyshare.com/v/81zlHQeG/file.html

ADB-files: http://www106.zippyshare.com/v/guVfwUn9/file.html

Tablet drives for windows: http://www106.zippyshare.com/v/ZKDhieSc/file.html

You are responsible for what you are doing!

Unlock:

On your Tab:

a.Go to Settings -> About Phone/Tablet and tap on your model number until the developer settings are unlocked

b.In developer settings switch “OEM unlock” on

c.Also allow „USB Debugging“

On your PC:

a.Download and install Lenovo USB driver

b.Download and unzip the adb.zip

c.With “USB debugging” enabled connect your Tab with your PC and let it install all drivers. You will be asked whether you want to allow adb access from this PC. Allow it and also check the "allow everytime" checkbox.

d.Go to your unziped adb folder, Shift + right klick in it and open a terminal in that folder

e.In terminal enter “adb start-server” and watch your Tab

f.In terminal enter “adb reboot-bootloader“ and wait until your Tab shows a orange Lenovo message

g.Check if your tab is in fastboot mode with typing “fastboot devices” in terminal

h.If your Tab is regocginzed correctly type „fastboot oem unlock-go“

ALL YOUR DATA WILL BE WIPED

i.Let your Tab reboot

j.You are unlocked now!

Create a nandroid backup of your tablet:

Before you start:

1. YOUR BOOTLOADER HAS TO BE UNLOCKED TO DO THIS!

2. You have to download the linked TWRP. It’s for X50M but it will work on our X50F, too

3. This method will not flash TWRP permanently, it will just boot the recovery without modifying anything

On your PC:

a.Download and unzip the TWRP.zip

b.Open up the folder and locate the “twrp.zip”

c.Let it open and continue on your tablet

On your tablet:

d.Re-enable developer settings and switch „USB debugging“ back on

e.Wait for the ADB prompt on your Tab and allow your PC.

If it doesn’t show up, retype „adb devices“ in terminal OR reconnect your tab to your PC OR do both. Just try

f.On your PC type in your terminal (with adb server running): adb reboot-bootloader

Switch back to your PC:

a.Check if your tablet is recognized correctly: fastboot devices

b.Boot up the TWRP recovery by typing: fastboot boot [path to your twrp.img]

Tip: Begin with “fastboot boot “ and just drag and drop the “twrp.img” from the folder on your PC to the terminal window. The right path will be insert automatically. It should look like this:

ADB>fastboot boot C:\twrp.img

c.Hit enter and wait for the tablet to boot in recovery

Back on your tablet again:

d.You will be welcomed with a message from the creator, just hit the “read only” button

e.Now you will see the “normal” TWRP main menu

f.Go to settings FIRST and disable the screen lock as it will cause freezes!

g.Go to “BACKUP” and choose your external memory (sd-card) as the backup location (I recommend this but it is not essential)

h.To have a full backup, check all checkboxes. Caution: On the right side is a small scrollbar, scroll down to see all backup checkboxes

i.Do a full backup and wait until it is finished

j.Go back to the main menu and open up the “REBOOT” menu

k.Do a normal reboot if you doesn’t want to re-enable OTA Updated,hit “Bootloader” if you want to continue to re-flash your system

Re-enable OTA Updates:

YOUR BOOTLOADER HAS TO BE UNLOCKED TO DO THIS!

a.Download the firmware and open the “SW” folder. You can ignore the other folders!

b.Reboot your tablet into fastboot mode

c.Check if your tablet is recognized by your PC by typing: fastboot devices

d.Navigate to the “SW” folder and start to flash the following images via fastboot.

(There are multiple system.img with a number in it.

ONLY USE THE BIGGEST FILE. IT IS NAMED “system.img”.

It is the same for userdata.img!)

cache.img

system.img

userdata.img

recovery.img

I’m sure that not all of them are nessacery to re-enable OTA updates but I flashed all of them to be safe

e. Flash the images by entering the following commands:

(you can use drag and drop again to get the right path to the images):

fastboot flash cache cache.img

fastboot flash system system.img

fastboot flash userdata userdata.img

fastboot flash recovery recovery.img

in the terminal on your pc. Don’t be scared if the system image takes long to flash. It is huge and will be send in multiple parts to your tablet. JUST WAIT!

f.After you have flashed all of them enter: "fastboot reboot" and wait

g.After your tablet is booted up, go through the start assistant until you are greeted with the home screen

h.Go to settings and open “About tablet” and check for firmware updates. Wait. It will download available updates and flash them through recovery

i.Done!

If you root your tablet you will be unable to to OTA updates again!

Keep OTA and root (some kind of)

a. After you set up your tablet and updated it to the latest firmware version, reboot in bootloader again before you root or modify your system!

b. Open a terminal and enter: fastboot boot [recovery file], so you temporary boot the TWRP recovery

c. Choose "read only" again and do a backup of your "system" partition only

d. Keep the backup

If a new update arrives and you are rooted just boot up the twrp again. Now don't use it in "read only" to restore your untouched system twrp-backup. Download and apply the new firmware.

Go to fastboot again and backup the new system. YOU WILL HAVE TO DO THIS AFTER EVERY NEW FIRMWARE UPDATE BEFORE YOU ROOT!

I haven't tested this method, I read about it in some other forum about some other Lenovo tablet. If someone wants to try this, report back please :)