I recently acquired a 15" TiBook from someone who no longer wanted it. He took good care of it and with the exception of a few slight surface scratches, it looks practically new. That being said...it won't turn on!! My question is -- does the battery need to be good for the unit to turn on, even if you've got it plugged into A/C power? The amber light on the plug comes on as if it's charging, and it never goes off. When I hit the little indicator button on the battery, nothing lights up. It would seem quite obviously that the battery is bad, but would that stop the unit from running off of wall power? If it's just a bad battery I'll gladly buy a new one, just wanted to check before I waste my money!