FR965 2 years use, battery suddenly goes 0% from 67%

Recently I found my FR965 goes battery 0% after 1-2 days, it displayed 67% (means 33% drain with 1-2 days, heavily used activity and wifi since i was testing it.) then 0%, turned off.

I've factory reset the watch but no imporvement, unfortunately warranty already expired. Is this expected life? I was using FR935 3-4 years before but never seen such short life.

Latest firmeware updated. anybody has same sympton? or anybody know battery management reset?