Bluetooth keyboard return key not working after holiday.

I took my Intel Mac running Ventura 13.4 on holiday with me but I did not take my bluetooth keyboard. On returning, I find the keyboard connects and works except that the return / enter key does not do anything. The battery level in the keyboard is OK. The return key is not recognised when I start in safe mode, though the return key on the regular laptop keyboard works. Similar answers suggest the return key probably gets more use than other keys, and may have worn out. This would not be impossible, but it seems pretty unlikely that the last keystroke that worked was just before I went on holiday. Is there another explanation?