Fisher & Paykel GW709 has no lights or beeps on power up?

Could anyone please tell me why my F&P GW709 won't power up? It doesn't do it's usual musical beeps and no lights come on when you power it up on the wall.
There is power to the main control board (measured on the back side of the plug in connector) and just to make matters a little more confusing, I've swapped both control boards (the one that the power enters and the one that the push buttons/LED's are on) with ones from another machine and it still has the same fault.
Please, please, please can anyone help