Pro 16 Plus PB16255, would not powered up from battery

3 mos. old Pro 16 Plus PB16255 would not powered up from battery, diagnostic test shown battery in good health, spent a few hours with tech support person whom insisted issue caused by AC adapter, tried different USB-C chargers, got the same result, battery level stucked at 58%, laptop shut off when charger unplugged. Issue was finally resolved by physically reset internal battery, all good now.