Thanks a lot iFixit for the guide! Just in case someone has problems with the click wheel after replacing the battery. It took me nearly a day to find out that the old battery had pulled out a connector when pulling it out. That’s the black little square in the middle of the flat cable. After pushing it gently down the click wheel worked again. I don’t know if anyone else has still an iPod Photo in 2020 and runs into the same problem, but just in case I thought I could mention it in the comments.