I've had my tablet on charge for most of the day. It has not been running, it's just been sat there on charge. When it starts up the lock-screen tells me to connect my charger... but when I do it goes *poof*. Not a clean shutdown, literally it just powers-off. If I try to power-on with the charging cable attached it gets to the green WowPad screen and then powers-off again. Any thoughts?