Diagnosis
The door lock mechanism (door latch assembly) has failed in the locked position. The three beeps indicate the control can't confirm the door is unlocked.
How to Fix It
Unplug the washer from the wall outlet for two full minutes. Plug it back in. The control board will perform a reset and usually cycles the door lock, releasing it. If the door unlocks, remove your laundry immediately.
If That Didn't Work
The door latch assembly itself is likely defective and needs replacement. You can manually release the door in an emergency. Locate the emergency door release cord behind the small access panel on the front lower right. Pull it firmly to disengage the lock.
Heads Up
Never yank on the door when it's locked. You can damage the door seal and the latch mechanism. release is for emergencies only; get the faulty latch replaced.