As said already... from a long tripp things can rock loos (or worse). What I would do and in what order:
1) Check for battery leakage and if any any I'd remove battery and clean up the mb (if exposed traces, check that they have connection through).
2) As others, I'd too then start pressing in all chips that are socketed so they are securely in place.
3) Remove all expansion cards from the machine.
4) Remove the harddrive.
5) Remove and clean cpu socket and cpu card and reinsert them.
6) Remove the zip mems.
7) Try another CPU card.
Remove mb and see if I can find any dammaged or dodgy components for easy replacement.
If it still doesn't work I'd put it away for spares, or in you're case, send it off for repair by pros.
