yetti 400 lithium not storing power from charger-wall


i yetti 400 drained to zero unattended and when i arrived, i plugged the charger back to wall, it has been 24 hours now of charging with all lights indicating watts in.... but after 24 hours the charging indicator still flashing at 20% ..... unplugged the charger after 24 hours and yetti 400 is dead.

how to reset? or is it the way? or is my lithium batteries dead?