Hi,
After a firmware downgrade my bios was bricked. I used the tools and bios from the website, the downgrade seems to be a succes, but after a restart the screen keeps black.
I managed to follow the guide “Flash BIOS with CH341A programmer” and i managed to load the firmware back on the chip. I was not been able to use the bios from the Lenovo website because the file size was to large. However i found a bios from a member of this forum and i used that one. After the bios flash i was been able to start Windows and load the latest official bios to my system. But i found out that the bios information like s/n, MTM, and maby some other things like UUID was changed.
Before i erased the chip i made a backup. And after the last bios update i made a copy as well.
So i have 2 .bin files. One with a bricked bios but with my original information, and one with a working bios with someone else his information.
I dont have problems to edit my bios file with a hex editor. But i am a bit lost now.
1) which information form my old bios file do i need to copy to my new bios.
2) Is there a guide somewhere how i can do this?
3) Is there a tool to flash this bios to my laptop without using the CH341A programmer again, i just finished screwing back 20+ screws 
My laptop is a Lenovo thinkpad Y540
Module with the GUID starting with FFF12B8D-…
Module with the GUID starting with FFF12B8D-…
I found this GUID
I used UEFI bios editor. I can export the GUID. And i can import this in my existing bios. Is this the right way?
This laptop will support Lenovo Variable Tool you can download it from this website.
Lvar tool can write Serial Number MTM etc very easily, i used that after having my motherboard replaced.
Hex edit is also an option but i did that on almost 10 year old laptop, so there might be some issue regarding checksum but LVar will not have any issues like that.
Thanks for your answer.
When i try to open the tool i get this error:
An error has occurred in the script on this page.
Line: 348
Char: 4
Error: Could not complete the operation due to error 80041010
Do you want to continue running scripts on this page (yes) (no)"
with this explanation:
The error (80041010) you are seeing here is due to attempting to access an invalid class (Lenovo_BiosPasswordSettings). This class should be available on any machine that supports WMI. Can you provide the models you are having trouble with so I can see if the WMI was properly set up?
But i dont know what to do with it.
This information is normally hidden in a padding, not stored in NVRAM (the GUID that was mentioned). It can often be restored from a dump of the bricked bios since these areas aren’t cheanged during an update.
For LVAR there are certainly several versions, location for this information did change during the years. Did you post your dump of the bricked bios?