Gateway NV52 Laptop Crashing during POST

I have already taken it apart, cleaned it out with canned air, wiped it all down with isopropyl alcohol, reapplied a thing film of thermal grease, reseated all the connections, and yet it still boots up for 10-20 seconds, and then crashes. I have it up on a ventilated laptop stand, so it remains around 50 Deg Celsius. It is not overheating. I am at a loss for things to do. I'd rather not take it to a computer store to be robbed of $100/hr for labor. I am good in soldering, basic hardware repair/installation so I'd rather do it myself. Any suggestions?

Gateway NV52
Windows 7 Home