Triangle of death - anything I can do?

Thanks for the reset procedure, I finally could reset it.

At least there was a backup from this morning and had nothing to set up.

But when this is fixed, I'm leaving the beta program.

Yes, device is off then. But as soon as I start it again, triangle loop is back ;-)

Here's how to fix this to update the software to version 21.22:


1) Download https://dropmefiles.com/604474 and unzip the file. This is the original Garmin firmware.

(For 255/255s/255s Music/255s Music/265s/265/955 and 965 firmware can be  found at:

https://dropmefiles.com/128355

)

2) There will be read_me.txt, gupdate.gsp and force.tmp files.

3) Reboot the BTOD device using the top left button, watch for the triangle.

4) Reboot the device using the 3 buttons: hold POWER, START, DOWN. You will hear a beep, immediately release POWER and START while holding DOWN. After the second beep, release the DOWN button.

5) The unit will reboot after approximately 10 minutes.

6) Initially set up the device, do not connect the phone.

7) Connect the device to your PC and copy the files from (2) to the Garmin folder on your watch. If you have macOS, use the OpenMTP app: openmtp.ganeshrvel.com/ )

8) Disconnect your device and confirm the update is installed (the watch will prompt for the update).

9) Go to connect.garmin.com, log in, select your device and settings in the top right corner, navigate to your device page and exit the beta programme.

10) You are now free to sync and update with Express (on PC/MAC) and GCM on your phone.

EDIT: new link for all affected devices.

To reset it I had to hold the Power button (light) for more than 15 seconds to turn it off.

Once off, I waited a bit (10 sec) to see if it was looping again, it was not.

Then I pressed and held the Start/Stop and Back buttons, I pressed and hold the Power button.

When the blue triangle appeared, I released the Power button, but still held the Start/Stop and Back buttons.

Then after a few seconds, it should beep, when it beeps, only release the Start/Stop button, keep holding the Back one.

Then it should beep again, and you can release the Back button and wait for the watch to complete the resetting process.

Keep trying took me 2 attempts. When it beeped I let go of the button about a second layer. Just do it nice and slow.

The download link doesn't work for me, is there a different site you can use? I can't access the site at all, at least here in Australia

Looks like it happens on 21.22 too so maybe a GPS sub-firmware issue.

Thx for our reply.
I have rejected this as answer as it's not a supported Garmin method afaik. I think I read somewhere they also suggested not to do it like this.
From programer point of view, as hardware modules' firmware was changed with some updates too, I think it's not a good idea to backdate to 21.xx. This might cause some side effects as modules' firmware might be different to what's expected from 21.xx.

On reddit as well: Garmin Forerunner stuck cycling through triangle screen : r/Garmin

You can do what you do. I have the unit working as instructed. More on the way... 255 /265 / 955 devices are affected. Garmin also received an email from me. It's good morning in the US today for Garmin SW developers