Thought I'd try updating the firmware. Oh dear. Grabbed the update app for MacOS, which - on Sonoma at least - is a dmg file that cointains a shortcut to Applications and a Contents folder (usually wrapped inside an .app). I ran the executable from the MacOs subfolder, which successfully detected the remote and allowed the firmware to be uploaded.
This failed - there was an error about boot loaders which unfortunately I didn't capture as I didn't anticipate any problems! Now no device is detected, and the remote flashes 3 red lights on button press.
Reading the advice on the forum that I should be able to recover from this in the app proper, I quit the updater and launched SkipApp. Nothing detected. Restarted a few times, same result.
Switched to a windows machine - again, nothing detected in either the SkipApp or the updater.
Any ideas gratefully received...