I have a similar problem with gear S3 classic. It worked fine for over 1 year and lately the battery drains from 97% to 2% in a few minutes. I factory reset it a few times and no difference. My watch takes awhile to boot it up and during setting it up as a new device it shots down. I called the teacher customer service the opened a ticket for me gave we a number and asked me call a provided samsung number. I was told that the watch is out of warranty so I need to pay for a repair or take it back to best buy, where I purchased the watch. Samsung does not care about their reputation. This is too bad. Shame on you. I even feel sorry that recently purchased a new S9 plus phone. They did not deserve my money.
Somebody needs to be fired. Google "Gear S3 Battery s**ks" and you'll see why.
Samsung took a perfectly good watch and ruined it. Mine is nearly 2 years old and it was just the latest "update" that hosed everything up. 4 hours and I'm done for the day. It's embarassing since I talk up Samsung line to all my Apple coworkers. They were all intially very impressed (nearly envious) of the Gear Classic watch. Now they chuckle at my frustration.
People are going to be dumping Samsungs if they can't get their head on straight and fix this probelm they so easliy created. And as far as all of the one-off solutions that people are trying on their own....hey Samsung, here's a suggestion and it starts with a message from you that reads "A new update is available to cure your battery headaches and we're sorry we hosed the pooch on this one"....
Please get on if and quit pretending "all is well" on these $350 boat anchors.
There is no way to reverse an update. I recommend trying these steps. They should be of help.
Dear @SamsungMod23, the steps written in the link you've given is almost equal to "do don't use the watch". And the funny thing, even when I take off the watch and let it lay on the table with everything off, the battery still drains fast. And yes I have the latest update and I did a full factory reset. And my battery was replaced a few weeks ago by Samsung service, I still have the issue. If you have any suggestions other than those, shoot.
This seems to have worked for me. The battery on my watch went from lasting 3 days to just 12 hours.
Now after this reboot it has lost 21% battery in 16 hours hopefully this will continue.