Instinct solar powers off randomly

I'm having the simular problem with mine that is two years old. It just randomly turns off without pressing any functions. Garmin should step up and make it right.  I can plug it into the charger and it turn on again. I'm very disappointed! 

Get in touch with Garmin support. They may offer you a refurbished watch with hardware update.

support.garmin.com/.../

I am also having this problem. It switched off at the end of a ride today just I I was stopping the activity and it didn’t save it. Now it it going off a few minutes into an activity. 

The sudden shutdown indicates that the battery has degraded so it can't support the power surges caused by things like vibrating for notifications, or turning on the GPS for recording activities. Turning vibrate off, just disguises the problem - it will keep getting worse and the watch will become unusable. My watch was out of warranty, almost 2 years old when this started happening and it's not acceptable for an expensive device to fail that early.  I tried everything, including factory resets, and then called Garmin support. They swapped it for a replacement watch. Garmin's response will depend on the consumer laws in your country - I'm in Australia and the consumer laws give you lots of protection if the product has an unreasonably short life, even if the warranty has expired.

It is a battery problem, mine being charged at 100% shuts down at every lap while the vibrating signal is on. The problem is that if i deactivate the vibration i have no way to do my intervals because the instinct solar has no sound and then i have no means to know when each interval is finished. Honestly i think garmin does it on purpose, none of my garmin watches has worked for more than 2 years without glitching. After 2 years you need to buy a new one.