Just try Garmin fenix5 and rest will be happiness
Samsung is very bad company when it comes to own issues. Gear S3 has loop reboot issue as many reported and I am.one of them, but ofcourse Samsung will never want to help or tell you.
I just bought Garmin Fenix 5 and supper happy, just guys try you Garmin fenix 5 and you will never eant to hear any Samsung watch... period
I posted a solution before but it was taken down. I replace the battery that I found I can't even mention where because they'll kill this post. Not only did it fix the reboot issue but i can even turn down the brightness settings. Everything works so much better. I think the reason it loops and I've had this problem before on cell phones is the battery is too weak to boot. That's when it's on the charger it's able to.
That is the fix. There are good videos online you can find that I can't put links to or anything cause I'm afraid post will get taken down.
I will say this forum is horrible in my opinion but I reposted cause I was tired of getting emails of people still struggling with issue and going around in circles. It's super easy to do you will just need a special Y as opposed to normal X philups screw driver to take the cover off. Take your time get the right little screw driver, watch the videos out there ( you know where) and get a replacement battery ( you know where ).
Good Luck. It will be like a brand new watch, even snappier and brighter.
One thing I would like to add is that this was the case wuth my watch and different things can cause reboot. For instance sometimes it could be pure software that something fails to load correctly. But if you do a reset and you have had the watch for a while with some heavy use, don't rule out battery. It's a powerful watch full of lots of functionality constrained to a tiny battery that must fit inside this little watch. It's actually pretty impressive, only 380 mha that's why it charges so fast. It's a V8 with a 5 gallon tank.