Why can't I get my jlwd1610 washer dryer to start?

Why can't I get my John Lewis jlwd 1610 (made by Zanussi I think) to start its wash cycle? ... All the lights come on and I can select a programme OK, but when I press the start button on the right the start/pause light just flashes green briefly, and the machine won't start the wash cycle. No error code is displayed, just the wash time for the cycle. Why will it not start? Would it be the door interlock, or its connection? Or the PCB? How can I tell, and could I fix it myself, or is it a job for an expert?