Forerunner 920xt looping on start screen

Hello !

I cannot start my Forerunner 920XT. It loops on start Screen without booting completely.

I tried many things :

- Trying to switch on when it is plugged 

- Hard reboot

- Empty the battery

When it is plugged to my computer (macOS), I cannot see it on Finder or in Garmin Express. I cannot even see it on bluetooth on my Garmin Connect app.

Did someone face this kind of problem?

Regards,

Dimitri Piriou