Well.
I guess it's not quite dead. You hear the 'bong' sound, and the apple logo appears and you can hear the hard drive spinning. However, the screen goes blank until you apply pressure to the area to the left of the touchpad.
Gratz, your GPU is loose - something some models of the ibook are known to be prone to.
Take it to someone who repairs them, it shouldn't cost a huge amount to get it working properly again.