I recently installed Beta 6 on my iPod touch 5th Generation, and it's been running fine. However, this morning it wouldn't turn on. I plugged it into my computer and it started charging. It seems that the battery completely ran out. It was about 80% last night. What could possibly take so much battery life while the device is sleeping? When it turned on, only two apps were in the app switcher: Gmail and Settings. What could have done it?