LG washer WM2140cw.
Nothing happens when press power button. No lights and no sounds.
Breaker switch and power outlet are fine.
I have tried this simple reset procedure:

Unplug from wall
Open door and manually spin drum 360 degrees (click is heard and display light for tone selection comes on for brief moment)
Wait a few minutes
Plug back in

The simple reset was ineffective at solving the problem.

I noticed if I hand spin the drum and repeatedly press the power button at the same time, all the lights on the display come on as if the washer were working properly but it is only for a split second then all lights go off.

Could this be a bad user and display board? seems to light up just fine for brief moment when hand spinning drum/pressing power button.

More likely the main control board? Any help greatly appreciated.

Alaska halibut fishing trip to anyone who solves my problem.

I know it's been a while but I'm hoping you see this. I have same LG model, & exact same problem. The LED light on my main control panel is lit and power is getting to my front control board. Was it the back main power board that was the problem on yours? I was about to replace the front control board but now I'm having doubts :(