Diagnosis
This is a door latch error. Three beeps indicates the control does not detect the door is properly closed and latched.
How to Fix It
Power cycle the dishwasher by turning off the circuit breaker for one minute. Ensure the door is fully closed; push firmly on the upper center until you hear a definitive click. Inspect the plastic latch hook on the door for damage and the strike plate on the tub frame for alignment. The door switch assembly may be defective if the latch is intact and aligned.
If That Didn't Work
A faulty door switch or a break in the wiring harness between the switch and the main control board can cause this. The switch can be tested for continuity when the door is latched.
Heads Up
Do not attempt to bypass the door switch. The dishwasher will not operate without this safety interlock engaged.