Ok, so I was in the gym the other day (yes, I was actually working out) and my iPod mini happened to fall out of my pocket and onto the floor. I was sitting on a bench, so I thought, no big deal, right? Well, wrong. It appears that the angle that I dropped it at or something caused a head error on the hard drive. So, I needed a new hard drive for my mini.
After some extensive research online (actually, I just did a google search), I found these instructions. That tell you how to take apart your iPod. I bought a new hard drive on eBay (and then I bought a second one too, the first of which may have worked, but I didn't try it enough) and was able to replace it. If you do this, make sure to try all and any combinations of hard drive cables and orientations. It took me 4 tries on the second hard drive to get it to work. I think the first replacement would have worked too, but I just didn't try hard enough.
Anyways, I took it apart, and put it back together (see photos). Now it works wonderfully! These instructions will work for batteries and click wheels too. I wouldn't be too scared about it. Really, once you pry off the top and bottom, it's a piece of cake. Make sure to use a hair dryer that gets pretty hot. The one I was using didn't direct the air over the iPod as well as I would have liked, and it took a while to soften up the glue. Good luck!