I changed the dispenser and it still does not open. Nothing is blocking the door. The racks are properly installed. Iran it several timeswithout detergent and it does not open. I reset the waher and it still does not open.

Is the rack in backwards? If not then you will need a meter to check the solenoid controlling that door.

Some washers use a solenoid, some use a heated wire clip. You will have to pull the inside door to check. The solenoid type use a small plunger pin to hold the door shut and retract at the signal. The heated wire use a U shape clip that expands when the electric signal send a current to the clip, heats and lets the spring snap the door open. When it cools, it allows the door to snap closed.