Frozen on first day

could be it rebooted and bootloader then faulted into neverending loop before starting watchdog again

Could be - it's possible that if the battery was basically flat it could have dropped out (resetting the Bangle) then come back and then the CPU locked up because of the low voltage.

It's a good point about moving the watchdog init code - I think I didn't have it earlier because I didn't want it to interfere with Nordic DFU's usage of it, but in a way it doesn't matter.

I'd be a bit worried about changing it because of one potentially freak event, but if this happens again - to @map or anyone else - I'll get it changed