Try the following,

Force to Mass Storage -
Turn unit off. Hold the lap/reset button while plugging the unit into the USB. Continue holding the lap/reset for 30 seconds and the unit should go to mass storage.

If you can get it to mount to the computer…

If you can power it off you can try

Force to Mass Storage -
Turn unit off. Hold the lap/reset button while plugging the unit into the USB. Continue holding the lap/reset for 30 seconds and the unit should go to mass storage.

Non-prompted Non-Vol C…

Open a support Ticket at Apple and ask what to do. Possible they do something different on the USB-Port on the new m1 (not Intel) Mac Mini.

Also open a support Ticket at Garmin. 

Did you look with the "Disk Utility.app" (show all Devices (Command-2)) if…

Hi,
Try the following on your PC (not on the MAC at 1st):
Force to Mass Storage:

• Power the device off
  
• Press and hold the lap button while plugging into usb
  
• Wait 10 seconds and device should go to mass storage
  

After if it works, do a full format (not quick…

There is likely a file in the NewFiles folder that it is trying to process on start-up that is causing the crash.

If you can mount it to a PC check to see if there is anything in the NewFiles folder. If so delete it. If that does not work you can try a…

If you can mount it to the PC then check that there is nothing in the Garmin\NewFiles folder.

Force to Mass Storage -
Turn unit off. Hold the lap/reset button while plugging the unit into the USB. Continue holding the lap/reset for 30 seconds and the unit…

Here are some tips I've come across at various times in these pages. I haven't needed to use them myself but  they might be useful.

1 - Soft Reset (all models?)

Press and hold down power button for about 10 sec or even longer.

 

2 - Force to Mass…