15.20 version Fenix stuck in triangle logo loop

Have you connected it via cable to Garmin Express on a mac or pc?

Yes but nothing ...

Does it see the watch, so you can try copying the RC onto the watch and force another update?

https://forums.garmin.com/outdoor-recreation/outdoor-recreation/f/fenix-6-series/241847/device-stuck-did-soft-restart-now-stuck-on-green-triangle-what-to-do Mentions how to do a FULL Reset

"

Power off the watch.

Power on then immediately press and hold top right and bottom right together.

Release top right on first beep, release bottom right on the next beep.

See if that sorts it out. If not contact Garmin Support unless you have already done so."

It solved! I tried a hard reset holding down/back-lap and Start keys. I power on  and at first beep release the Start button, at second beep release the back-lap button and after 1-2 seconds I release the down button. The watch continue to boot passing triangle logo and stuck on loading fit files. Then i power it off and holding back-lap button i power on the watch. Then all did well and the 15.20 update finish successfully!

Great stuff! I can imagine you had your heart in your mouth for a lot of that, glad it's working!

Yes, when i did everything and nothing dis ok, then i felt disappointed. All good in the end