DIAGNOSIS The control lock is activated. This happens if the Control Lock button was held for 3 seconds, usually by accident during cleaning.
FIX Hold the Control Lock button for 3 seconds. It's the button with the padlock icon, usually on the far right of the control panel. The 'Clean' light will stop flashing.
IF THAT DIDN'T WORK Unplug the dishwasher from the wall outlet for 2 full minutes. Plug it back in. This resets the electronic control. Try starting a normal cycle.
HEADS UP If it flashes again after a reset, the touchpad itself might be faulty. Moisture can get behind it. You'll need to replace the user interface control panel.