Unfortunately I didn't fix it I just had to replace it
Sometimes it seems that the problem can be fixed just by unplugging the machine for 24 hours (not switching off, really disconnect it from the power grid).
In my case instead I believe the problem was the electric motor that drains the water. I was suggested to make it run by connecting an external wire to it. Then my wife was harrassing me and I just ditched the whole thing in the dumps, and bought the cheapest possible Candy dishwasher (Italian brand now made in China). Not the right approach I know but faster
By the way, Bosch is not made in Germany any more and the quality is much lower than in the past. Not worth it IMHO