How to test individual parts of an iPod classic?

I bought an iPod for parts recently. Is there a method of determining which parts are salvageable and which are not? I get an error screen each time I try to restore the iPod and i can't sync it without first restoring it. I have followed all prompts and suggestions for trouble shooting given on iTunes but have come up empty-handed. I assume the screen isn't a problem due to it seeming to function well so far and I already replaced the battery. Could this be a hard drive problem?