1. New backs aren't always made well, often with the mounting posts not lining up as well as they should.
2. New batteries are a crap shoot. Most don't last as long nor are rated as high as advertised. On the 5g and later, you can put in a much larger battery in them, but you need the thicker case.
3. If you mod an iPod mini, use a higher quality sd to compact flash adapter. The cheaper ones, end up having weird issues when transferring files.
4. If Rockbox seems temperamental it's not just you. It can take a bit to work out the issues it has with your iPod, from buggy themes to random crashes.
5. If your music doesn't play right through Rockbox (clipped music) or playing music on rockbox seems to crash device, the issue was the file transfer. To fix, reboot the iPod to the stock Apple Firmware, delete the old files, and then transfer them again. Apple firmware handles file transfers much better than Rockbox.
6. If your iPod hasn't been charged in a long time, it might not come up when first connected to power. Sometimes, leaving the iPod attached to power for a day or two will allow it to get enough charge to get into actual recharge mode. Older models re