If you have tested the on/off switch and thats switching over and sending 230v to the control board then its looking liek the control board is the fault here.
Have you tried removing the wiring blocks and refittng then to check there isnt a bad connection?
Also remove the board and open the plastic casing and inspect the board. Check fo any signs of burning on there or blown tracks that you could try and repair with a soldering iron.
But if that looks all ok and there isnt a bad connection on the wiring then its going to be the control board itself. As there isnt anything else in there that can cause this fault if the power supply to it is all ok.
In this case you will need to replace the control board and that should cure the fault from there.