I-pod wont charge or switch on. ?

i have what i think is a second generation 20gig i-pod that will not charge or do anything. It worked fine then just wouldnt charge ran out and will not restart. I purchased a new battery for it and fitted it but still nothing. I have tried different charging leads. even ones from mains rather tan from my computer still nothing.. I assume it is a fault inside the part where you plug the charger etc into it? any one got any hints or tips?