Extract latest firmware and search for the known version code, search your dump at the corresponding address
If that doesn’t work:
Check ucode versions with MCE to get a time window, then use a hex editor to compare.
This is a general advice, I don’t remember everything from this thread, if an update did go wrong you may have parts of two firmware versions in your dump
Replying to notify of success!
My steps were as follows:
I got the programmer and 1.8v converter; my model was a CH341B, not A; however, I compared it to an “A” and it had the same chip on the PCB, just different pin out on the pins for jumpers, etc.
I tried to extract the bios using windows and AsProgrammer, but it wouldn’t detect the programmer; I then succeeded with a new install of Ubuntu 24, and used the flash ROM utility as described here: [Guide] How to Use a CH341A SPI Programmer/Flasher (with Pictures!)
I used md5sum utility on Linux to compare the hashes of several bios chip reads, both without removing the chip clip and after removing and replacing it to confirm it wasn’t misaligned.
I compared the extracted Bin to the latest Lenovo bios: I used a tool (I think linked above?) to extract the .CAP file from the Lenovo EXE, then UEFITool to extract the .bin file from there.
I used HxD to look at the files; I searched for “IdeaPad” and found the section with my serial number.
I put this section into the extracted Lenovo bios; I didn’t try to copy across the other section that posters above said looked important.
I flashed this back onto the chip as per the winraid link I referenced above.
I read this back from the chip and compared the md5 hash for what I read and what I intended to flash, to check they were the same.
Then it worked!
My takeaways: