MacBook Pro shut off and won't come back on

I was in windows installing iTunes and my computer cut off with no warning. I have swapped hard drive, reseated the ram and everything. I have a 2008 unibody Mbp the first one that came out.

What could possibly be wrong with it?

 

I've tried those things. Swapped the hard drive, reseated the ram, everything. No weird smells but I do remember being in Windows and the fans running pretty hard. Now when I try to cut it on I think I hear a faint click that is with the back cover removed. No pulsing light on the front or anything.

Think the logic board is gone in this thing? If so, do I have to replace it with the same one or can I get a newer one?

 

It turned out to be the battery. Thank goodness.