Apple watch series 2 shuts down often even with complete charge and hard reset does mot work

My apple watch series 2 has been working well recently until it started to shut down and say either it needs charge or no light will come on until it touches the charger even though the apple watchs charge is around 80 and 60 percent full . I have tried the hard reset by pressing both buttons for 15 or more seconds but it does not work and it keeps shutting down middle of the day and is quite annoying because i cant monitor my steps or look at notifications or control music from afar pls help i want. My money worth the exp anyways thxxx hopefully someone related