Let’s say, theoretically, that my AirPods Pro case’s battery died. Let’s also theorize that an official Apple repair lab examined the case, and returned it with this exact reasoning, mentioning that it cannot be repaired and a new case can be bought (as it is a 15 months old case, it is no longer under the warranty).

How would one get a new pair of battery cells to replace them? Would love to have this as a personal project.