What happened to me was that after downloading the new software version, I confirmed the update, but the watch just restarted without the update. So I had to confirm the update again and only then the watch updated to the new version. I then performed a soft reboot.
update: I realized I had recently used garmin express to update the maps; and the reboot happens shortly after the "loading maps" boot screen.
So I just went into garmin express and removed the US and EMEA maps from my watch and... no more reboots yet (multiple minutes while before this would have rebooted in seconds)
hope this helps someone else if they hit this reboot loop
