Bios Mods -The Best BIOS Update and Modification Source

First time posting -if this is answered somewhere already, or belongs somewhere else, please let me know.

I'm trying to roll back a Lenovo x240 from 2.40(GIET90WW) to 2.35(GIET85WW).  I've tried both the update utility and the CD/DVD install (using the ISO), and in both cases I'm getting a message that "BIOS image file does not match this system."  Since I have not made any hardware changes on the system, I believe it's due to the following (from the Lenovo release notes):

"If the UEFI BIOS has been updated to version 2.36 or higher, it is no longer able to roll back to the version before 2.36 for security improvement."

I am assuming this is not a technical limitation, but rather one that Lenovo has imposed to keep people from going back to a less secure BIOS version.  Is there a way around this?  Since I made no hardware changes, I didn't think a whitelist modification was relevant, but I'm hoping there is some similar that can be done to force the downgrade.

Cheers,
Christian

I was able to dig into the BIOS upgrade files from Lenovo and run the following:

winflash64.exe /sd /file <path_to_.fl_file>

This allowed me to install the old BIOS version without the package checking the build date first. Worked perfectly.

(11-24-2017, 02:05 PM)_NULL_ Wrote: [ -> ]I was able to dig into the BIOS upgrade files from Lenovo and run the following:

winflash64.exe /sd /file <path_to_.fl_file>

This allowed me to install the old BIOS version without the package checking the build date first.  Worked perfectly.

I really thank you for that solution. It worked for me as well but it was kind of tricky to figure out what you mean.
So for anyone who has even less knowledge than me, do:


Download version 2.36 and try to install it. It won't work however but the files have been generated at least.
Open cmd.exe and run:
C:\DRIVERS\FLASH\gjuj23us\WinFlash64.exe /sd /file C:\DRIVERS\FLASH\gjuj23us\GJET86WW\$01DF000.FL1
The paths can vary I think so be carefull

All I can say is _NULL_ saved me from bricking my ThinkPad