I had 2 iPods. One refused to play at all the other refused to hold a battery charge.
The plan was to replace the battery in the working iPod and at the same time swap over the back case from the broken one since it was engraved.
It's difficult to work with those small ribbon cables and the associated connectors.
After making the repair I tried to charge up the iPod. No go. It still does not fully charge or hold a charge. So, not sure if there is a bad connection or perhaps the problem was not the battery but the charging circuit. Unknown at this point.
It will play music and it sounds fine using headphones. However, plugging it in to a base unit, like an iHome, gives playback that is broken up and eventually the iPod locks up.
I think my only advice would be to get a good set of magnifying goggles and a well lit work area (especially if you are not young and still have really good vision...I'm not young anymore :( )