Two electronics repair guys I enjoy watching on YouTube are British. Mend It Mark is in England, while Graham of Spare Time Repair is now in the U.S.
By chance, Graham and Mark each recently tackled the same model CD player. It’s instructive and entertaining to compare how they go about the process of troubleshooting. (No, I haven’t yet replaced the battery in my Pixel 4a phone.)
Graham’s player had previously been worked on by somebody else and, it seems, modified. It couldn’t be fixed.
Mark’s player had a different set of problems. It was restored to working order.