Sorry to hear you're having trouble with your unit. Just to make sure its really fully charged, have you tried charging your new sd on one of your old sd chargers? Sometimes the center pin on an sd charger can get pressed in far enough to not make a proper connection so the battery appears to be fully charged when it's not. There's a 2 week warranty on most units excluding fluid damage. I'd suggest you call the store tomorrow (we're open Sundays now). If nobody is able to troubleshoot and fix the problem for you, ask for an RMA number, and we'll be able to send you a new unit after inspecting the old one.
Thanks- Jared