[Android Q&A, Help & Troubleshooting] celt0368:
Unfortunately the above did not work for me. I've been trying to revert my Lenovo S8 50F back to kitkatt after recently upgrading, used various tools (Phone Flash Tool, IntelAndroud FBRL lancher.bat etc etc). and now after thinking I'd re-isntalled kitkat, find I have Boot failed: EFI Hard drive.

I've tried the above repair_Bios.rar and the following ensues:

12/09/17 15:32:06.037 INFO : Loading Flash file (C:/Temp/Lenovo/3/repair_Bios/flash.xml)

12/09/17 15:32:06.039 INFO : GP_Flag is set to 0x80000045

12/09/17 15:32:06.040 INFO : Ready to flash!

12/09/17 15:33:08.012 INFO : Port 1/1/3: Flashing OS

12/09/17 15:33:08.037 INFO : Port 1/1/3: fastboot -s BaytrailEB1FBC19 -S 100M flash osloader "C:/Temp/Lenovo/3/repair_Bios/efilinux-user.efi"

12/09/17 15:33:10.168 INFO : Port 1/1/3: fastboot -s BaytrailEB1FBC19 -S 100M boot "C:/Temp/Lenovo/3/repair_Bios/droidboot.img"

12/09/17 15:33:12.966 INFO : Port 1/1/3: sleep 25000 ms

12/09/17 15:33:37.966 INFO : Port 1/1/3: fastboot -s BaytrailEB1FBC19 -S 100M oem wipe ESP

12/09/17 15:35:38.178 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem wipe ESP"

12/09/17 15:35:40.180 WARNING: Port 1/1/3: Retry to execute fastboot -s BaytrailEB1FBC19 -S 100M oem wipe ESP

12/09/17 15:37:40.423 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem wipe ESP"

12/09/17 15:37:42.425 WARNING: Port 1/1/3: Failed to execute non mandatory command fastboot -s BaytrailEB1FBC19 -S 100M oem wipe ESP, ignoring error

12/09/17 15:37:42.426 INFO : Port 1/1/3: fastboot -s BaytrailEB1FBC19 -S 100M oem wipe reserved

12/09/17 15:39:42.657 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem wipe reserved"

12/09/17 15:39:44.658 WARNING: Port 1/1/3: Retry to execute fastboot -s BaytrailEB1FBC19 -S 100M oem wipe reserved

12/09/17 15:41:44.904 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem wipe reserved"

12/09/17 15:41:46.907 WARNING: Port 1/1/3: Failed to execute non mandatory command fastboot -s BaytrailEB1FBC19 -S 100M oem wipe reserved, ignoring error

12/09/17 15:41:46.907 INFO : Port 1/1/3: fastboot -s BaytrailEB1FBC19 -S 100M oem start_partitioning

12/09/17 15:43:47.156 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem start_partitioning"

12/09/17 15:43:49.157 WARNING: Port 1/1/3: Retry to execute fastboot -s BaytrailEB1FBC19 -S 100M oem start_partitioning

12/09/17 15:45:49.363 WARNING: Port 1/1/3: Process TIMEOUT Failed to execute ""C:/Program Files (x86)/Intel/Phone Flash Tool/fastboot.exe" -s BaytrailEB1FBC19 -S 100M oem start_partitioning"

12/09/17 15:45:51.370 ERROR : Port 1/1/3: Flash failure

The tablet is stuck on "Normal Boot" with an andoid lying on its back and door ajar. FASTBOOT CMD WAITING....

I couldn't perform TABS8-50_Otkat as the Phone Flash Tool can see no img file. Its an xml and .fv file.

Any advice please?

:(

After spending 10 hours on this, I think I'll be flinging into the snowy garden tomorrow.