Fenix 5+ battery drain

Hi all

I have been having serious battery drain issues for a while now. I have performed numerous soft and hard reboots and installed the latest FW 12.0. The watch will function normally for a short time then it will start to turn off and on randomly through the day. The Bluetooth connection drops randomly and the battery drains by around 30 to 50% per day sometimes. Other days I get maybe 3 or 4 days max. I am not using any activity trackers except for the basic step counter and mobile notification which I have used for the past two years without any issues. 

I have seen other posts regarding similar issues but no resolve as yet. Any advice would be greatly appreciated.