I charged my iPhone fully at around 2:40PM today. It said I had a full battery power, all day long and just now (12:28AM) it just shut off on me. It didn't give me any "20% left" or "10% left". I was on the phone today for at least 40 mins altogether and played for about an hour. And I've recently un-jailbroken my phone from an un-jailbroken back-up. Any reason why this happened?