Power and startup problems w/ 17" G4 A1085 powerbook

17" Powerbook G4 (A1085) does not power up from the adaptor: a little noise is heard when the power button is pressed, and there appears to be power since the numlock and capslock light up but nothing else. It does power up from a battery with startup chime, but never fully boots - just the black apple w/ whirling wheel under it. Tried booting from a Leopard install disk (holding down the C-key) but the CD just makes a few noises, then falls silent and I'm back to the black apple and wheel. I guesds there are 2 separate problems: won't start up from the adapter, and won't fully boot nor boot from an install disk.