Shelly BLU Door/Window frozen

It’s not directly openHAB related, I hope that’s ok?

My Shelly BLU Door/Window was completely frozen (the software, it’s about 18°C in here) this morning. After much trouble (resetting, removing the battery…) the device suddenly worked again. Not that happened right after a reset or something; it was a mysterious miracle.

But now it’s frozen again… :frowning:

Does anyone have any experience with this issue?

Apparently, this led me to the solution: