I have an 80 GB Ipod classic, when placed on a docking system it plays normally but the minute I take it out and wanna use it as is, it won't turn on at all. It is fully charged (based on the dock) and when I try to connect to the iMac, Itunes won't even recognize it. It flashes on and off with the logo. I tried to reset based on the basic troubleshooting, Nothing happens. Please help.