Did disassemble but didn't see diagnostic lights
Yes, I did take apart - not really that bad - just have to be patient and use anti-stat wrist-strap plus YouTube videos.
I also did continuity test on the power button and its cables - all fine. So I go along with you on the MLB.
Still, it would be nice to narrow it further - at least so I can sell working parts and ditch non-working.
So - the diagnostic lights - where are these to be found? I've read a few things about them but nothing that says anything about them on an A1174 Core 2 Duo 20.