My 2008 X5 was running fine until this morning. It cranked, ran and died right away. After that, it just cranked. No error messages, just showed the Exclamation "!" and engine signs. Last night when I filled up, I shut the engine, but still left the key in so my daughter could listen to the music, after a while all the lights and music went dark. I started the car and it ran fine till this morning. Please help if you know.