Amanda's dashboard

My M1330 laptop is 16 months old (and 4 months out of warranty). It's been fine, although occasionally it will force itself to reboot overnight. Last night, I used it for a while and put it down, still fully powered on, and left it alone - this morning I picked it up, it was powered off, and so I pushed the power button - nothing. Dead. The battery is still fully charged; all of the little green LED's on the back light up. I don't think the battery is the problem, it's the extended battery and it's still good for 4-5 hours of normal use. Any advice for me? I am not a hardware person, I am a software developer, but I can do hardware work if I have really good instructions to follow; I added the bluetooth module without problems.