won't power up

Model is F4V309WNW. Intermittently the machine will not power up. Nothing, no tone, no display. Deadsville. I've tried reboot sequence, even tried spinning the drum to wake it up.

I replaced the PCB and it has been ok for a month. Yesterday, nothing. I managed to get it to work by holding the power button and continuously clicking the wall plug on and off. I'm assuming it's not the power filter because the LED on the PCB is lighting up.

Surely not another faulty PCB.

Maybe I need a rubber hammer!

Thanks for any ideas.