Wow that stinks
I was going to recommend let it sit on charge for a while, since the Sonys when they are fully drained take a while to even show a charge light (which often freaks people out), but clearly you have tried that.
I think the thing that makes that stressful is knowing the minimal stock of the nook that is out there. With Kindle, Amazon is always good even if their stock is low, and even though Sony's support stinks, it's easy enough to take it to the place you bought it and swap it for a new one.
I hope B&N helps you out, and quickly!!