I found the solution! After years having the same problem with a lot of dead flics I bought a tool that is meant for changing clock batteries. Here is the tool on a norwegian site: https://www.kjell.com/no/produkter/elektro-og-verktoy/verktoy/spesialverktoy/klokkeapner-p48329?utm_source=google&utm_medium=cpc&utm_campaign=NO | Shopping Category&utm_id=23554678753&gad_source=1&gad_campaignid=23554678753&gbraid=0AAAAADcA9cwe4JDhSc1gGT3C9cnKFt7KA&gclid=Cj0KCQiA49XMBhDRARIsAOOKJHbbqrwuH_gRu4oZXdGMoGy7YnlvONWAxdkLhBYV0sBsJEmm1b35O_8aAqvpEALw_wcB