Kitchen Aid dishwasher will not start

I have a built-in Kitchen Aid (about 6 years old) and it had been working fine but we tried to turn it on last night and none of the buttons would respond except the Cancel button. When we hit the cancel button the cancel button light came on and there was a humming noise so I think we are getting power but the dishwasher would not start no matter what we did. And none of the other buttons seem to do anything.