My s3 frontier battery dies in 3 hours and when i try to charge it overheats and have to take it off and on. All this was after last update. Since then i have replaced the batter the watch back and the charger still same thing . This has become a $300 paperweight.
I have been loyal to samsung 2 tvs watch several phones including my note9 now earbuds and my watch. But the watch issue is very concerning.
I definitely can understand the frustrations with this. For best practices with this device, make sure you keep the watch updated at all times (check manually even if you have it on auto-update) When you work out with the device on you may want to take it off afterward to give it a chance to cool down. Wearing it in places wit excessive heat may not be the best option. If you wear the device while you sleep try to ensure that you are not sleeping on it as your body heat may overheat it as well.
For your battery draining fast give this link about battery life a shot: https://www.samsung.com/us/support/answer/ANS00078033/
If this began after an update, try resetting the watch right away. (this should be done after every update as well as every now and then just to keep the device running smoothly)
If the device is causing pain, bruising or has something similar to visible smoke coming from it please send me your full model code and serial number via private message right away.