The older Xbox 360s were like time bombs, don't beat yourself up about it, it happened to a lot of people, but there are so many places that can repair it for free. Hell I think even Geek Squad has started doing it, but since you are still under warranty you should just send it in to MS.
Call 1-800-4-MY-XBOX
In about a week you will receive a playboy in the mail, that's mine don't touch it, then you will receive a box. Put your 360 in that box and send it back to MS, they will get it back to you ASAP, Sadly for them that's another week.








