Servis washer/dryer (M9409W) problem?

Power module on this machine has blown when pushing the button to operate the dryer cycle. I cannot establish why this happened despite a 'bang' when the button was pushed. The machine is in good order and had little use. I am sceptical about obtaining and fitting another expensive module if the same could happen again. I have traced the wiring to/from the controls/module but cant see anything obviously wrong, but dont have a wiring diagram to check if existing wiring is connected correctly. How can I check this out please to prevent a re-occurance?