Fisher & My Paykel Smart Drive 703 has an intermittent starting problem?

Since new the washing machine has had two remanufactured control boards, a rotation sensor, and two hot water solenoid valves installed. Now it sometimes refuses to start.
The board powers up on start, but every now and then there is no response when the "start/pause" button is pressed. Continuing to press the button, and then the power button, and turning off the power for a few minutes, after a delay, which could be up to 30 minutes, the machine will start and perform normally.
What do you think is the cause of the problem, and how can it be fixed?