The Red X

My son's 80gb iPod gets a red X, with the Apple support site listed. I've tried going through the suggestion of putting it into disk mode and then rebuilding it, but it won't even go into disk mode. Is there anything that can be done? Or is it basically dead? It is still under warranty so I'm not going to crack it open. I'll let the geniuses do that. I'm assuming a bad hard disk, but it could be anything I suppose. I think that everything on it is also in iTunes so he won't lose anything if it is.

Since it's still under warrenty, I wouldn't try to do anything with it, just send it in to Apple.