At this point, I'd just take it to an expert to have a look at it. You seem to have done a lot already to no avail. If you need it back up and running soon for college purposes and whatnot, just pay someone who knows what they are doing to fix it.
Can you not return it to the manufacturer for repair? Or have you voided your warranty by all that tinkering around?
Oh yeah, and btw, I mentioned it already but something similar happened to an old machine i was using to mine. Crapped out, wouldn't boot from HDD or CD, so a friend of mine who is an electronic engineer looked at it and said that the BIOS battery had been fried. He replaced it and everything was working fine again. Maybe not relevant to you, but just thought I'd pop it in since you are running out of ideas.