What happens a lot on these is the wires in the door break.
Remove the wooden door and then the outer metal door.
Behind there you will see the wiring harness. It will run into a plastic holder going to the underside of the dishwasher.
Open the plastic casing and then give each wire a tug and check for broken wires in there and repair them.
As in the past ive found this fault were it wont fill and it turns out to be a broken wire in the door loom.
So check that first and see what you find and let me know.