Three things to try:
1. Try zapping the PRAM by holding down command-option PR when you try to start up.
2. Try booting off of the recovery DVD provided with the computer.
3. If he/she can access the RAM modules and/or Airport card on the computer, make sure they are seated firmly. This last one bedeviled my Dad’s powerbook for a week post soft drop until discovered.....
Command-Option-P-R doesn’t work unless the thing actually bongs and tries to start. You *can* reset the Power Manager, though - but instructions vary on model.