Garmin instinct 1 turns off rendomly

I have a Garmin Instinct 1 solar surf which was working fine for 1 and half year and now the watch turns off after starting any activity,  also when it’s vibrating and even turns off just randomly. 

what I tried:

• turning off vibration

• hard reset

• reset to factory default + delete all my data.

This did’t fix the problem.

It’s very disappointing for a watch costing 350€, I won’t buy Garmin again if this is not fixed, my watch is less than 2 years old.

Any ideas on how to fix this? Is it related to a software update?

Thanks