freezing on a loading maps screen and restarting

Check here for the Factory Reset Instructions. You will loose all data since last synchronization and all watch settings.

You need to perform these steps shortly after device power-up, before it automatically restarts.

forums.garmin.com/.../reboot-loop---device-not-usable-any-more

Same today! Drove to a run spot, got all warmed up, fired up the watch, and it reboot cycled for 20 mins before I gave up and went home. Even tried those reset instructions several times and it kept rebooting when trying to load maps. Now it's downloading a massive maps file on the computer which I hope fixes it. Pretty pissed off right now, though.

UPDATE 1: Updated to 18.23 and most recent maps and it's still rebooting over and over. This is apparently a dead $600 watch now. Great job, everyone. Factory resets do nothing.

UPDATE 2: Had to update to beta 19.09 in order to fix this watch. What a mess.

Factory Reset worked for me. All the data is still there (including learned HRV status etc.)