Bosch SRS55L22GB/01 D/W – Module problem

Called out to a Bosch SRS55L22GB/01 8-place dishwasher. Half way through wash it had “died” per customer. No display, no activity. I verified that the mains voltage was getting to the on/off switch and that it was working ok, and the door micro was working OK. I took out the module, and took the cover off, looking for blown tracks etc., but it looked visually perfect. Could it still be blown, even though it looks OK? Apart from a click (water valve noise?) when switched on, the machine appears dead, no lights, no display. Should I buy a new control unit? (as we know, they are expensive)
I cannot think of any other reason for a dead machine (loom looks fine BTW). Anyone know of another possible cause other than module blown (as I said there is no visible damage to module – blown microprocessor maybe?)

Additional info: across the large 2-wire plug (red/grey-black I think) that goes in the module there is a low voltage (around 20). Should this be 230 volts there?

Thanks for your wisdom.
Mike