I have a PowerBook G4 12" with 1.5Ghz, with 1GB of RAM, and OS 10.5 Leopard. It worked just fine up until I installed Leopard on it. It goes "bong" and the caps lock light, and HDD spin up, but nothing on the display. I took it into Apple, and they claimed it was the logic board, and it would be $600 to replace. Anything I can try like reseating cables?