I have the EXACT same problem on my PB100.

Got it off Craigslist a year ago and fired it up no problem. Took it out again a month or so later and black screen.

I can hear the drive spin up (which it wouldn't do when I first got it until I gave it a few good whacks)

I'm reluctant to start taking things apart without having a more targeted approach to fixing it.

Please post back with any results!