Vivoactive 4s 100% on charger and dead immediately after taking off charger

My wife's vivoactive 4s just died on her wrist yesterday. The battery wasn't low at all. She plugged it into the charger and soon it read 100% charged. When she removed it from the charger, it immediately died. Just a blank face. Upon plugging it back into the charger, the triangle shows up and the watch restarts and shows 100% charged. It operates properly while charged, but is immediately dead when uplugged. I have cleaned the charging connectors and done a factory reset to defaults. After going through the setup, it showed 100% battery charge. I removed it from the charger, and the same thing - dead. Any ideas or suggestions?