Oh that happend to meee o:
You have to contact the people who make xbox by web or phone (I used web) Something like xbox.com i should say a website on your xbox when you turn it on, When you get a hold of them they ask you to send your xbox back to them and if you havent sent it before you get it free, so send it out theres instructions on there and they send it back fixed or a new one
Good luck