Yes the heater box (part no: 491756) incorporates a water point diverter valve so likely as not it’s jammed. Easy to check if a dishwasher has that type of valve, just lift the top spray tube clear and looking down into the heater box nozzles you can see the cam plate clearly if it has one.(might need a torch though?) 😉
I’d also check all the chips on the control module to make sure a faulty valve hasn’t taken out its control chip. If you look at all the microchips closely , you may see one with a corner of its top blown off……and if it is , you’ll need a new module as well.