Electronic panel lights up, nothing els...

LG Dishwasher LD-4050W When turning on, at times, all I get on the dishwasher is the panel illuminated, pushing the knob to start the washing cycle nothing happens, just a ding sound, pushing other buttons same result. Have found to leave it overnight mostly, and then off it goes without any other problems. It is like power is getting to the washer and that?s it, why it works hours later or the next day has me baffled.