A few days ago my nook was completely charged and I had no problem charging it. I charged it last night which was fine I let it charge until the light was green then I unplugged it and turned it off. I went to turn it on this morning and it was completely dead. I have had this nook since December. I have had it charging in the wall for a hour and it still says wait 15 minutes because the battery is too low. I don't know what to do.