I bought a used iPod nano on ebay and the battery didn't work (they didn't tell me about that part)so I decided to try and fix it.
I have used a soldering iron before so, I thought how hard can this be. Watched the video acouple of times. It was very straight forward. My iron might have gotten too hot, but I soldered the wires and put the back on and shazam it turned on and I could listen to several songs in a row and the battery is still charged. One glitch, there is a black line on my screen now. But I can still see everything and best of all I can listen to my music.
Make sure your iron dosen't get to hot. There is a thing that controls the heat, but I didn't use it and can't remember what it is called.