Forerunner 955 solar kept updating then wrist HR not functioning

Problem started a few weeks ago my 955 solar kept updating itself, each update lasts 1 min so felt like unusual. Didn’t have time to explore… then from yesterday the wrist HR sensor stopped working. No green light (or any light) from the back of the watch, checked Health and Wellness the wrist HR was “auto on”. Tried checking for any software update on the watch but not couldn’t! Tried restarting the watch and not helping neither. 

according to Garmin connect app the software version is  26.08 (DFU-6695ea). 

May I ask what next steps I should take to rescue this poor watch please?