dishwasher wont engage program after water shortages and water being cut of?

Over the last week we have been haveing water shortages. today the relatively new zanussi built in dishwasher model number zdt6503 wont engage the program. I thought this might be down to no mains water but this is not the case, I have pored water into the dishwasher to see if it will drain and it does when the program is started but then emits a beep constantly and the program stops. I am ownderign if this might be something similar to a safety system built in water pumps for showers when there is no water available. Any suggestions?