Just replaced my Gear S3 battery (24$ + 10$ for tools). Excited to get 3+ days back. Links in comments, will report back with new battery life in a few days. : r/GearS3
9 Tips To Prolong Battery Life On the Gear S3 (Tizen 3 0 Battery Drain)) - YouTube
Fix for Samsung Gear S3 battery drain issue begins rolling out - GSMArena.com news