Verified answer

You may have auto-off enabled. Go to system/console settings if its a 360 or system if its the original xbox.

The 360 turns off automatically after 6 hours if not used. There's a setting on the system blade to change this if you don't want it.

well, just call the company, you can find their number on internet. tell them what happend and if they can fixed it, maybe they can fixed free if the first time. try it, thats what i did.