Powerbook G4 Titanium Motherboard needs power

Something like a year or more ago by now, I purchased the bottom of a broken Powerbook G4 TItanium 15", for the case parts, and it came with a motherboard that the seller thought was shot. Anyway, the Titanium finally got to the point where I wanted to take it apart and replace the case parts, and I wanted to try out the motherboard. It turns out that it works fine while it has power, but it doesn't get power throught the power socket, so it just worked till the battery drained out. I put the first motherboard back in, but I'd like to know if there's a way to repair just the power circuit on the semi-working motherboard. Anyone have an idea where I could/should start?