Why can't I get a picture?

My friend asked me for help in fixing his console. From what he's told me, these are the problems he's facing.

The system froze up in the middle of a game and he restarted. After that, the system worked for a bit, then the screen resolution either distorted or went white...a kind of brick pattern. There are no beeps on powering up and no yellow light. We can't even get to the restore/reset screen. Any ideas what could be wrong???