My Iphone is stuck on apple screen and keeps resetting.

Hi

My mate gave me his Iphone to fix as I am normally good with these things but this one has me beat.

Its stuck on the Apple Logo screen and it intermittently resets.

The PC or Itunes doesn't pick it up.

I've tried putting in DFU mode, Tried Hard resetting and tried turning off just using the Power button. Nothing worked. I can't even turn the phone off. When it resets its self its blacked out for just half a second then boots the logo again.

I've tried recboot, Tiny Umbrella and redsnow to try and boot some life into it but still it stays on the apple screen.

Its seems to be looped into reset.

I've tried loads of times to enter DFU and to turn the phone off etc but no luck.

I've tried different cables, USBs ports (and I no they all work) but nothing.

I appreciate brains on this one.

Cheer
Jas