Resetting the dishwasher

If there is a procedure to reset your board it would be to remove power, then restore power to the dishwasher and press certain combination of buttons within certain number of seconds. As far as I remember that procedure was available and was described in tech documentation for Whirlpool, Kitchen Aid and Kenmore dishwashers. I don't recall such procedure for LG.
The tech documents are usually under the kick panel, which is under the dishwasher door.
The "hard" reset procedure for any control board would be the following sequence (standard electrical safety and common sense rules apply):

• remove power (unplug, turn off circuit breaker, etc.)
• access the control board
• make a picture or descriptive list of all plugs and wires connected to the board so you could reconnect those later
• make sure you don't have an electrical charge on yourself - touch the grounded part of the dishwasher, usually the frame
  
• CAREFULLY (you can damage your board) disconnect all plugs and wires from the board
• with a large flat blade screwdriver or any other metal tool insulated from your hand, briefly short the connectors on the board. If you can identify where the power wires connect to the board - short those between each other first.
• put all plugs back using the picture or the description you've made before disconnecting; put the appliance back together. turn on the power.