Delonghi Dishwasher keeps turning off/wont stay on?

My Delonghi Dishwasher DW47s/w keeps turning off. The dishwasher is turned on at the power point. The water is turned on. Okay
When I press the POWER botton on the front it wont stay on. I have to keep my finger on the POWER button and then press the START button for washer to work. If I do this it will then pump out any water in the bottom and start to work. ***BUT when you take your finger of the POWER button the washer just turns off and stops working. Do you have any idea what could be the problem please.