I tried to fix my ipod screen on Saturday - and killed the whole thing instead.
The case is difficult to open - you have to go for it, you can't pussy foot around otherwise you'll never get it open, and you'll scratch up the case. I'll post instructions if i get time. Once you've got it open any fixes are pretty straight forward, apart from where I went badly wrong.
Anyway to cut a long story short, I changed the screen and it still didn't work. This meant that either I'd been sold a duff screen, or that the problem was with the signals sent to the lcd. Without another ipod I can't tell which is true.
Now, here comes the important bit. The metal half of the case containing the headphone socket is attached to the motherboard by the flimsiest of connectors. You can remove it but you have to be VERY CAREFUL other wise the headphone connector and the ribbon cable part company, never to be joined again.
I would suggest that if you change the battery or hard drive (both of which are a piece of piss once you've got the case open) then you do not try and take this connector out).
Its only if you are unscrewing the motherboard to get to the front that you should ever try and take it out.