one quick check if you have a multimeter is to check the pins coming out of the cord out of the power brick for voltage, (be carefull no to short them or them to the shield). you could also lick it but that would cause it to be a very much worse day! PLEASE DON'T!!!
Anyways check the back of the laptop for any signs of damage to the power socket, if none, then RMA is your best bet. I had an 8880 that did the same thing towards the end of it's life, my solution was to unscrew the battery unplug it and short all the battery contacts in the machine. (there was a capacitor that stayed energized and screwed up a starting transistor). Since your system is under warranty and I'm guessing (might be wrong) that you have little circuit bord repair experience, I'd RMA and get a new one in quick so you can get back to the fun.