Hii, i want to buy an old apple ipod. Ive decided on an ipod nano 4th gen or an older mode like the ipod classic, but im not sure which one to get, so i was wondering which one would be best in case i need to get it fixed in the future? For example if the battery wears out or something else inside it needs fixing, which one would have the best chance of surviving, since its going to be an old device. Thank you!