My dishwasher has had light use in 3 years but suddenly the start button won't light so I cannot start a cycle. The other buttons light. Hitting the normal/heated dry buttons several times will get all the lights including the start button to light and then the washer automatically runs a series of short cycles which show the water and pump are working. After these short cycles are done I hit the normal cycle button which lights but the start button will not light or start. What is wrong with the machine?