Whirlpool Dishwasher ADP4500 - starts but will not run

My Whirlpool Dishwasher ADP4500 has not been used for a year until a month ago when it failed to run but having poured some very hot water into the sump it ran fine.
The same thing happened 2 weeks later but on the third occasion today, even with the hot water it failed to go beyond the initial pumping phase.

I held in the start button for a few seconds and it tried but failed to overcome its inhibitions.

The soap has not been released yet.

Any suggestions, please

Thanks

start light should be flashing. count the flashes.