Another vote for secondhand, if you can.
Dishwashers are disposable. Not within a short timeframe, but eventually they wear out beyond practical servicing.
My in-laws were told this by the second consecutive Miele dishwasher repairperson who agreed with the first one that their near $2k dishwasher was well beyond repair and they would be better off replacing it. to their credit, it was run 2x a day, every day, for nearly 5 years and then 1x a day until it died on year 9. (7 kids + plenty of dinner guests).
The control board may be the issue now, but what about the pump, or the valves, or the heating coil? All these will eventually crap out. Our dishwasher (well, our landlord's) is literally rusting away. As in, the racks are disintegrating. They won't replace it unless it's broken but it's only a matter of time until a big piece of the rack gets through the filters and into the pump.
Finding a similar (if not newer) model that's used but in good condition is probably better than hoping you've fixed your own.