Lenovo Legion Y540 – Need help repairing BIOS after bad downgrade

[gestalt.exe]

Hi everyone,

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:

1. Downloaded stock BIOS BHCN39WW from Lenovo
2. Trimmed it to 16MB
3. Extracted the BIOS region from the corrupted dump
4. Extracted the BIOS region from the stock 39WW
5. Replaced the corrupted BIOS region with the stock one (within hxd , opened the corrupted dump and replaced its region by the stock)
6. Injected back my LDGB / DMI data from the corrupted dump into the new merged file (i've realised that replacing the region entirelly did delete the dmi data on the corrupt file)
7. Flashed the merged file → laptop boots again

I’m unsure about one thing, should i have just injected the DMI into the stock BIOS BHCN39WW?
Since my original dump was corrupted, and the EC still shows version 21WW, I want to confirm that my merged BIOS does not still contain corrupted structures from the old firmware,given that i used the corrupted dump as a base where i injected stock region first /reinjected only DMI values later
Could someone please verify the merged file or correct it if necessary?

I’m attaching:

• corrupted dump (16MB)
• stock 39WW trimmed to 16MB
• both extracted BIOS regions
• final merged 39WW file (with my DMI reinjected) (named finalflash)

Any help or corrections are truly appreciated ,
This is my first time repairing a BIOS so I apologize if some of my questions don’t make perfect sense. Thank you in advance for your patience and guidance.
Thank you!