If it's a 1st or 2nd gen Xbox (circa ~2006), wrap a towel around it.
http://www.wikihow.com/Do-the-Xbox-360-Towel-Trick
It works because older Xbox's had bad soldering that gets brittle and cracks over time, and heating up the board makes the solder flow and re-attach itself. Works much like the videocard/motherboard in the oven trick.