Last nite I used my iPad 3, put it to sleep and went to bed. This morning it wouldn't wake up. Put it on the charger, but still didn't come on - no indication that it is charging on either of the Apple chargers I use. Left it on one then the other for hours. Also tested the chargers with other devices. Have cycled the wake/sleep button, to no avail. This unit has been treated well - no drops or liquids. Kinda obvious to suspect the battery. Is there a way to test it? Reset it? Other ideas?