The Kenmore dishwasher (model 665 74363K2) is frozen on 'lock'. It's in a rental home where the tenant for the past 5 years only used it twice. We found some dead ants inside the panel and vacuumed them out as much as we could. Still can't get it to work using the press and hold for 4 second instruction.

Look at these: https://dl.dropbox.com/u/8010163/Whirlpool_Kenmore%20Dishwashers.zip
You need to check the micro-switch on door lock with a meter.

Thanks for the information! We have a tech coming out today. He gave an estimate of $300-$400 depending on what needs to be replaced. I was hoping for some trick to unlock it. Looks like it might be stuck buttons - perhaps multiple -based on the manual you provided.

Some of the buttons can be fixed, depending on the design. If the buttons are like the ones on a TV remote you just peel off the sheet of rubber holding buttons and clean it and the circuit board with soap and water then alcohol and it's like new, exactly like you clean a TV remote control.