Contact KitchenAid for service if these steps do not reset the dishwasher and stop the flashing “Lock” key pad; the control console on the dishwasher may need to be replaced.
The lights on a KitchenAid dishwasher do more than simply indicate when the wash cycle is done or what cycle was chosen. The lights will also flash when an error has occurred to let you know something is wrong and needs to be addressed, depending upon which lights are flashing. If the "Lock" light is blinking, the key pad itself may be to blame.
Touch and hold the "Control Lock" or the "4 Hour Delay" key pad (depending up on the KitchenAid dishwasher model) for four seconds to release the control lock feature.
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Use a lightly dampened cloth to wipe the control panel and clean away any residue that might be causing one or more of the keypads to stick in place.
Open and close the dishwasher door firmly.
Disconnect power either through the power cord or by shutting off the circuit breaker. Wait five minutes and restore power.