It could have happened in the post mate, if it got dropped or something then that could easily have knackered it.

As I said before, I buy, sell and repair ipods - replacing HDDs, LCD screens, click wheels, batteries etc etc, so if you need any pointers about replacing the HDD (if thats what you wanna do) then let me know. Its pretty easy and can be done in 5-10 mins on a 4th Gen.

For the price of a HDD, its probably worth selling on eBay as faulty - it will definately sell for a decent price. Then just buy another one off eBay. Thats the best option