My car has a key that has a non-replaceable battery. When it runs out, it’s trash. Replacement is a few hundred euro, lasts about 3 years.

Last year I opened it and desoldered the dead cell battery. That worked, but sadly I damaged the case.

Today, I fixed that.

Behold: the pink case that is easy to open (and replace). Def not waterproof, but should keep this thing running for a while yet.

The screws need replacing but I had no other M3 thread ones.