Diplomat ADP 8242 4th light flashing won’t start

Hi, in need of some help. I have moved into a new house, it has a Diplomat ADP 8242 dishwasher, read the manual to no avail.

When I press the black power button on, within 3 seconds the 4th light/LED only flashes (the normal wash program light) and two beeps.

I’ve tried following the reset instructions found in the forum here (power on black button, press program button 4 times quickly) but nothing changes.

I’ve tried waiting for the LED to flash before pressing the program button 4 times quickly, and also before the LED starts to flash to press program button 4 times quickly before the beeps are heard, but the LED still flashes and the dishwasher emits 2x beeps then the LED keeps flashing.

Does anyone have an idea what could be the problem? Am I following the reset procedure correctly? Is this a repair job or is there another way to reset it and get it working?

Thanks
Dave