Garmin lily 2 not tracking heart rate/sleep

My Garmin lily 2 version 5.1.0.21 and the green lights that I assume track heart rate and sleep patterns have turned oof. This is the second time it has happened. I reset it two weeks ago and the watch my tracking my heart and sleep as expected (lights on) and now it has stopped again. I have turned it off and on and the green lights did not come on. Thank you in advance