Computer Won't turn on

[Jack Bruss]

My Dad has a problem with his computer. It won't turn on - that is the hard
drive doesn't spin, the fan doesn't go on, and the power light doesn't go
on. My Dad said that a few weeks ago it would not turn off, but as of about
1 week ago it won't turn on. We took the case off and played with the
switch, but still no go. I've checked the power cord - it's ok. I'm
wondering if it's the power supply or the switch. What's a good way to
diagnose a problem there? Is there something else it could be? We replaced
the battery.

Thanks,

Jack