GE Dishwasher

after selecting start, machine fills with water to normal level, then there is no noise indicating washing cycle started–silence for the wash cycle time period. then a normal drain cycle completes, another fill, no wash. monitored three such cycles, detergent module door did NOT open, tho can be opened easily with manual button. ran Service Mode: all functions operated normally, including Main Pump, arms spun, EXCEPT Detergent Door did NOT open in Service Mode either.