My garmin instinct solar for the past few months have been shutting off by itself even though there's still 18-19 days of battery life, and it would just die off when I start any activity (seems like few people face the same problem). So I decided to call garmin service centre and they advised me to turn off anything that involves vibrate(yes including notification), and so far for the past 1 week everything seems to be working well except the fact that there will be no vibration which is actually quite useful when you're running. Hopefully this will work for some of you. Cheers.
