BIOS update from Linux for Lenovo Thinkbook 13s g2 itl

You need to download intel ME driver, BIOS and ME firmware update installers: https://pcsupport.lenovo.com/lt/en/products/laptops-and-netbooks/thinkbook-series/thinkbook-13s-g2-itl 

Download windows 10 iso: https://www.microsoft.com/en-us/software-download/windows10ISO

Then you need wine to run those installers in Wine, select "Extract only". Then the installers and firmware apps need to be overlaid on the winpe.iso, which is made from the win10 iso as described there:

https://wiki.archlinux.org/title/Windows_PE

Then you mount winpe.iso and copy all the files to the FAT32 root partition on the USB flash. Copy EFI folder from the original Win10 iso.

After booting to USB flash drive (ENTER, F12) you go to firmware update directory and run respective ...Flash/install.bat

Then you need to enter BIOS Setup (ENTER, F1), and "Load Optimized Defaults".

After that you can update ME firmware the same way, booting from the USB, "...Flash/MEUpdate.bat"

Lenovo A806 GApps installation

http://forum.xda-developers.com/showthread.php?t=2397942

Mini modular package. "pa_gapps-modular-mini-4.4.4-20150117-signed.zip"

Lenovo A806 New rom install (via TWRP)

Copy "VIBEUI_V2.0_1501_7.80.1_DEV_A806_NK_W_07B8.zip" file to Internal storage.
Reboot to recovery, wipe cache, dalvik, system, data.
Reboot again into recovery.
Unmount /cache.
Install ZIP.

Mount /system.

Rename /system/reovery-from-boot.p into something else does not work, had to reflash recovery. Finally deleted this file.

Reboot System, Install SuperSU? -> YES.

Lenovo A806 Recovery install

With SP Flash Tool: switch ON the option "DA DL All with Checksum".
Mark "recovery", select recovery.img from TWRP_Recovery.

The phone must be powered off, no battery. Click "Download", insert the phone cable.

All sound buttons + power to switch on the phone (cable ejected).

Lenovo A806 ROM flash readback

The phone arrived from China with a buggy altered firmware:
Hardware : MT6592
Model : Lenovo A806
Build number : VIBEUI_V2.0_9432_ST_A806
Build date UTC : 20140807-112632
Android  v : 4.4.2
Baseband v: A806.V30, 2014/07/31 14:53
Kernel v : 3.4.67 (buildslave@xmws58) (gcc version 4.7 (GCC) ) #1 SMP  Thu Aug 7 19:24:27 CST 2014

To backup the original firmware you need:

1) Preloader driver for MTK
2) MTK droid tools
3) SP flash tool

Backup process:
1) Get scatter file with MTK droid tool and phone switched on, debugging enabled
2) Eject the cable, power off the phone, eject the battery
3) Open SP flash tool, select the scatter file, go to the "Readback" tab, add new, put the number from the "Cache" partition start into the "Size" field.
4) Press "start readback", insert the battery, attach the cable.

I got a 1.4GB ROM file in 32 minutes.

http://www.theandroidhow.com/2014/05/how-to-backup-rom-dump-mtk-android.html
http://forum.xda-developers.com/showpost.php?p=44509214&postcount=407