My phone was purchased refurb around 6 months ago. I think maybe there's a hardware issue.

I've downgraded/upgraded from 1.1.4 to 2.0.2 to 2.2 to 2.2.1 many times. Every time it seems to work, and the screen updates during the restore process (see the progress bar etc), but when it should go to the home screen it just stays on the Apple logo with a circling wheel.

The funny thing is that itunes recognizes it, and even sets it up as a new phone (as if it is at the home screen), but the actual phone screen is still at the apple symbol with circling wheel.

I've also tried upgrading/downgrading the baseband with no luck.

It did come up after a few weeks of non-use, but wifi address was invalid, I fixed that, but since it started the apple symbol again. It's as if something overheats and the screen stops functioning...

Any ideas?
Thanks!