Favorit 50870 goes blank!?

Our 4 year old machine sudddenly refused to power up. Did a quick check of the obvious - plug fuse, power at socket and then opened up the front, tested mains through on off switch all OK. No obvious cable faults and water etc OK. Now at this point suspecting the pcb. Switched mains off and went to bed - prepared to buy a new one next day. Turned on again next morning and the thing powered up! Ran one wash cycle OK switched off and then refused to switch on again. Any ideas???