I have a 12" 1GHz PowerBook that's a couple years old (very light usage). All of a sudden a couple weeks back it wouldn't get more than 10-15 seconds into boot without kernel panicking in various ways. Same story booting off CD or FireWire, without extra RAM or AirportCard. So. Took it to Apple Store, guy says "whoa, needs a new logic board. Apple will fix this for $1300." [computer worth maybe $600 in top shape on eBay].
So I figure I can replace the logic board myself, at the cost of only a new logic board.(~$300, from a reputable local seller). Followed detailed dismantling instructions from ifixit.com. Replaced logic board and reassembled computer. Logic board is the correct type (1GHz G4)-- no funny business with upgrades, I just want my laptop working again. I was anti-static wrist-banded the whole time.
Close it all up, hit the power and... nada. Well, something. It does turn "on" as evidenced by the Caps Lock light toggling after hitting power. Holding down power for 5 seconds turns it "off". I did this later with the top casing off and observed that at the time it turns "on," the fan spins for less than a second, and then stops. No other action happens-- no hard drive spin, no audio, no video. I've checked all the connections, but to no avail. Same story. The fact the the fan and keyboard are getting power implies that the basic assembly went OK.
Is the new logic board worse than the old one, or does the behavior suggest a particular problem? I don't want to throw good money after bad, so if this project doesn't work, I'll have to throw it all away and get a MacBook Pro, but I'd really like not to...