My Lenovo Legion Y540 (i7-9750H, RTX 2060) bricked after I downgraded from BHCN44WW to BHCN21WW.
Laptop stopped booting entirely.
I used a CH341A programmer to dump the corrupted 16MB BIOS.
i then attempted the following:
- Downloaded stock BIOS BHCN39WW from Lenovo
- Trimmed it to 16MB
- Extracted the BIOS region from the corrupted dump
- Extracted the BIOS region from the stock 39WW
- Replaced the corrupted BIOS region with the stock one (within hxd , opened the corrupted dump and replaced its region by the stock)
- Injected back my LDGB / DMI