I have access to 4 of the 5 now (2 broken, 1 on my road bike that's working and 1 that's not broken but on a bike with a broken wheel & a trashed RD hanger, so not seeing any use for several weeks already):
Broken: 250123
Broken: 250123
Working: 250123
Working: 250123
...
Maybe more interestingly full numbers 250123XXXX0119 / 123 / 122 / 133. I blanked out the middle, idk if it's sensitive or not to share the serial #.
You are in the EU? I am familiar with the physical analysis of broken electronic units.
I can't of curse guarantee anything, but if this failure is due to a water ingress or internal dewing event there should be visible traces on the printed board. Sometimes it's also possible to see bad solder joints.
Internal damages of components unfortunately very often do not show any signs of something which can be seen visually. Sometimes they show discoloration on pins or melted housing but that's not always the case.
This analysis is very often destructive,. But .. its already dead, right?