Well, I'll tell you one thing. Don't ever buy from there again. That site, just by reading that page, looks to be a huge scam/piece of crap.
I'm guessing he fried something, but it wouldn't be GPU because it still boots to the Windows screen. Uhm. The BIOS(capital S...) should be fine, as it still boots up. BIOS stands for Basic-Input-Output-System. If the BIOS was shot, the computer would fail to post.
You could try replacing the motherboard to be sure, but I don't think it's worth it since the computer is bad anyway.
Maybe someone else will have a better answer, cuz that really confused me lol