My Kenmore dishwasher will not start and it is only 5 years old

Check to be sure power is being supplied to the unit. Then check the door switch for proper operation since the door switch is like a main power disconnect and if it fails the DW will do nothing.

There is also an inline fuse (attached to the plastic housing on the board) in the console to the right of the door switches. Use an ohm meter and check for continuity. Flat about 1 inch wide with 2 leads. Replace if there is no continuity. If the replacement comes as a kit make sure you put the kit in as the instructions say or the new one will only work a few months.