G4 powerbook is powerless...?

A few months ago I had to get a new ac adapter for my powerbook because the old one broke. It worked fine right up until a few weeks ago and then the ring that lights up when the ac adapter is plugged in stopped working and the computer stopped charging. I would take it back for the warranty but the day i got it the plug in to the computer got stepped on and bent out of shape. It still worked but I'm sure Apple would point to that and not give me a new one. So what i'm wondering(before I spend $80 on a new one or rip into the old one) is if it's the ac adapter or could it be something in the powerbook itself.
thanks in advance