iPod Classic 80GB is corrupt how do I fix it

My iPod Classic 80GB is corrupt I can't switch it off its stuck in the do not disconnect with a flashing circle centre screen. I tried pressing the centre and menu buttons to get the apple logo and then the centre and rewind buttons to get the diagnostics page. I ran the manual diagnostics and all tests were ok until it gets to HP detect with a 0 value, it displays press menu to continue but menu does nothing, I have gone back through the tests but it is still the same, is it possible to fix this? any help would be greatly appreciated. It does not go to the normal start page so I cannot get it to the factory reset and iTunes freezes when I connect it.