Re: SMEG DWF409ss
Almost certainly a corruption issue of some sort – mains suppressor is possible, the dispenser unit is a “big bad wolf” on these things, even the motor start/run capacitor starting to break down can cause issues.
However – without physically replacing components, it is impossible to work out whether or not the pcb is damaged, or just corrupted by the other components.
As a professional repairer, I carry a selection of components which allows testing by substitution. This can prove to be an expensive route for the home repairer to take as SMEG components are on the expensive side.
Sorry to sound a bit negative, but there just isn’t an easy answer to your problem.
Penguin45.