Toshiba L50-A no 640x480 resolution

[sparker1]

I am a noob at this so sorry if it sounds like nonsense.

I replaced the screen of this laptop (Toshiba L50-A) with a different brand of screen but with exactly the same specs. All I got on the screen were two shades of grey split horizontally. The supplier says the EDID needs repair.
The symptoms are :
There is no Toshiba splash, no access to the bios and, because windows uses 640x480 in the start up, I can't install windows. There is no display on an external monitor for the same reason.

I was able to install linux mint as linux must use higher resolution or bypass the edid somehow for their installation.

When Linux boots I go to a grey screen, as mentioned, before the higher resolution drivers are loaded and then i get the linux splash screen and a normal boot from there.

Linux mint is fine for me but the laptop belongs to a "windows friend" and one day access to the bios may be needed. Is there any way for me to fix this problem? Any guidance on how to do it would be greatly appreciated.