iPod Classic 120gb wont work

iPod displays "restore with itunes" message but when connected wont be recognized and after all troubleshooting steps finally got to connect it but try to do a restore and it says error 1439.

I think it is a hard drive problem but i dont know for sure. I took it to an iStore and they cracked it open but say they didnt know what was wrong and that they couldnt help me.

I dont know what else to do. Please Help ME!!!