Q: iBook g4 turn power on hear fans black screen battery charges but no keyboard or indicator lights? Help

Have you tried resetting the PMU?

http://support.apple.com/kb/HT1431?viewlocale=en_US

It could be a bad logic board.

How do you know that the battery charges?

If it's the DC-in board gone bad, it usually will not charge the battery.

It does sound like a professional evaluation is the best course of action.

Good luck.

P.S. Please let us know what the shop figures out. It could help someone else in the future.