Ariston LSI 61 stuck?

My dishwasher (ARISTON LSI 61) stopped in the middle of a cycle of wash leaving some water at the bottom. I tried to restart it by switching off then back on the same programme. It did not move (not even hear the motor running). My husband reset the programme by turning screw in the front of the machine. Thus, I started a brand new cycle which stopped at exactly the same point. Let me say that we had a technician last month that changed the serpentine for the same problem but I have a feeling it was resolvative. Can I do something? How much will it cost me?