usb device not recognized when plugged into computer

I have the same problem, I'm a repair center and I'vs seen two ipods like this, the aren't recognized by the computer, nor being able to charge it via USB, although when I hook it up via firewire cable I'm able to charge them, what I'm unable to do, is to transfer an sync content.

I think it's something wrong with the logic board, as I've seen this happened with other USB devices like pen drives that have "died" on me for no particular reason, if it wasn't detected at all I would think that it's a physical connection problem, with the cable it self, but if it's recognized as an unknown device it's probably an issue within the logic board, specifically of the usb communications chip/area.

Sadly my clients usually think it's a cheaper (cost/benefit) to buy a new one instead of investing in fixing the old one or they just use it with the music.

Thoughts anyone?