Ipad didn't seem to be charging very fast so let it totally run down and turn off. Plugged in the charger I have always used and it now tells me it is not charging. Tried another charger and I don't get a not charging message, but, after a minute or so the ipad emits a slow pulsing beep and the battery icon flashes. I have no idea what to do to charge this thing. Will an ipad charge if it is turned off? Any ideas?