After few day i find out solution how to install custom ROM to my Lenovo tablet. I think its first guide how to do it because every other guides were for TB2-X30F but not for TB2-X30L.
Installation guide: FILES TO DOWNLOAD: ALL FILES:https:// drive.google.com/drive/folders/1heVQAryphuXNVt5k-HsUhfRrVr9MV34D
ALL LINKS WORK ! JUST DELETE THE SPACE BEFORE drive.google.com...
1) On the tablet, at Settings, you must activate on the Developer Options the Bootloader Unlock (OEM unlocking) and USB debugging. Uncheck Verify apps over USB.
How to unlock Developer: https: //youtu.be/g5wkFAWDsg0
2) Download these files directly to your Android device, not to SD card.
a) https:// drive.google.com/file/d/1230xFbPA7DOGMhuX59yagEd6w1gNCI4o/viewSuperSU-v2.79.zip (for me working only v2.79)
b) https:// drive.google.com/file/d/1vRW5RZixtNVfKbJ7nL2EUetANydfmLNg/viewGapps.zip (open_gapps-arm-7.1-micro-20180721)
b) https:// drive.google.com/file/d/13Mp8guzzOvb17s88IQyez_9reozpTNbw/viewboot.img (from LiOS14-UNOFFICIAL-TB2-X30L)
3)Power off completely the tablet.
4) REMOVE SD CARD ! (because for me a part of system was installed on SD card).
5) Make sure you have a good cable so the connection between PC and tablet is perfect.
6) Download https: //drive.google.com/file/d/1XTDYs7kxagj-CXHsH_yyQnMXqYwAP_hK/viewADB and Fastboot to your PC .(here are the drivers too).
7) Unzip the zip archive and run with Administrator the apps from inside of the zip. To all the questions you must to press key Y to grant all the rights it needs.
8) Press and hold Volume up and plug in usb. Now you are in stock recovery menu.
9) From stock recovery select reboot to bootloader by using volume keys and power keys.
10) Wait about 5-10sec to tablet boot in bootloader mode. (shows lenovo logo in screen when ready)
11) Download the https:// drive.google.com/file/d/15IH55DgmD6SmlILjTukGeNcmYgUPcmCg/viewrecovery.img(its TWRP version for Lenovo Tab2 x30f so it wont work properly) and copy it into folder adb at local disk C (installed on step 7)
12) Run CMD with administrator and type cd C:\adb to select the adb folder.
13) In cmd type fastboot unlock-go and press enter. In case this command does not work, please try fastboot -s or fastboot oem unlock-go or fastboot oem unlock .
14) Flash recovery with command fastboot flash recovery recovery.img and then type fastboot boot recovery.img
15) From TWRP select Install and browse to emmc folder and then to your folder where you stored all files you downloaded.
(in bottom right corner you have Images... or Zips... here you can choose what type of file you want to install.
16) Now in menu select Wipe -> Advanced Wipe and check Dalvik Cache, Data and Cache. Wipe them.
17) Go back to menu and select Install. And install boot.img. At top of display check Boot and flash it.
19) Download https:// drive.google.com/file/d/1MlDxidIqLOZv_QZ91i8bsHgGdBMf7l9g/viewLiOS14-UNOFFICIAL-TB2-X30L.zip and copy it into folder adb at local disk C (C:\adb).
18) Go to Menu select Advanced and open ADB Sideload. Go back to CMD on your pc and type
If its your tablet properly connected you will see some letters and numbers and sideload. After that type
adb sideload LiOS14-UNOFFICIAL-TB2-X30L.zip
Now wait for finish the installation. If its installed corectly you will see Succesful at the top.
19) Repeate step number 15 and again install SuperSU-v2.79.zip (In installation you will see Boot image patcher)
20) Unplug your tablet from PC. And reboot it. First reboot may take 5-10 minutes and can reboot few times. DO NOT INTERRUPT THIS PROCESS.
21) After first start (set language, date..) Turn off devices.
22) Power on devices to recovery mode
(Press continuously the volume up and power key. When the screen on the tablet has started, release the power key and keep pressing the volume up key)
23) Now select again Install and install Gapps (open_gapps-arm-7.1-micro-20180721.zip). Then reboot it.
Now you have installed LiOS14-UNOFFICIAL (Android 7.1), with all stock apps(gapps) and also rooted device.
The tablet can also run on LineageOS 16 which is Android 9.
As I saw that the guys in the Russian 4PDA-Forum had been able to create a LiOS16, I was able to make some adjustments and compile a ROM with most recent security patches which now runs on my good old TB2-X30L / TAB2 A10-30: