I bought an refurbished iPod Classic 80GB off a guy on yahoo. When I first got it, the hold switched messed up within days and I couldn't take it off hold. I sent it back to th guy an he replaced thehold switch and put in a new battery. Since I've gotten it back, it will not charge on the computer or wall chargers. It says it's charging when it's plugged up but when you unplug it, the battery life is the same as before. It will never go dead while on the charger but it won't charge. When I plug it into my car charger, it charges quickly to alittle less than half and quickly drains after being unplugged. Why is it doing this?