The battery on my 9630 (Verizon originally) seems to be dead. I get the X through the battery icon when I try to charge via USB or charger and it will not take a charge.
Is there any known issue with the charger (different socket from my Canadian market BB's I see), battery, socket or...??
Did you let it run down past 20% more than a few times? your issue is typical of a battery damaged by running it past 20% many times. Lithium batteries do not like to get that low on a regular basis. They seem to work best when kept topped up when you are near power.