I'm posting here for the benefit of future seekers of these answers... having just been through extensive troubleshooting on this issue.
The WM3667HW has a four-wire door lock. It is often, but not always the cause of problems. IF you have replaced the switch, and find that it's the main board that is the problem, perhaps my experience will help.
Inside the switch has a small solenoid and a bimetallic strip which provide the mechanical motion for lock/unlock.
In my case, I went through a lot of trouble with the switch before discovering the issue was the main board.
Here's the pinout for the switch:
Black -- upper section of the main contact
Red -- lower main contact -- bimetallic strip -- solenoid
Blue -- solenoid (with resistor in circuit)
Yellow -- to resistor that heats bimetallic strip
You can figure out how it works by observation, but the practical upshot is that you can bypass the door lock altogether by jumpering the black and the red together.
This is NOT SAFE since the door can now be opened during a wash cycle (messy) or spin cycle (can rip your arm off).
However, if you love the washer, don't have kids and are competent enough not to open the door this will work.
If you want to take a shot at repairing your NLA main board, this is what I did:
The main controller board for my WM3667HW, part number 6871ER1003E is no longer available. It is potted in some kind of silicone. This is both a good thing and a bad thing.
The good part is that it makes it rather easy to spot parts that are burnt --- it darkens the goop and in fact makes it black and runny if the component gets hot enough. In my case it was the diode right next to the on-board transformer. I replaced it with an uprated version.
-- use a dremel to gently cut off the back of the plastic housing behind the bad component. Gently peel it up from the goop, do not stab into it!
-- Use automotive brake-cleaner to soften the goop. This will soften it without damaging any of the components or traces on the board. Apply liberally and often, soaking as necessary.
-- CAREFULLY use a pick to remove most of the goop. Strenuously avoid actually hitting the circuit board
-- Use a stiff-bristled brush to get the last bits off. A gun-cleaning brush (mil type) is pretty ideal. A stiff toothbrush will do.
-- Repeat on the frontside of the board. You may have to remove other components to get to the bad one. I had to remove the transformer.
-- Fix your board!
I love this washer, and it's no longer sold. It got some tough reviews and LG stopped selling because many people don't know how to use them, but for me it's awesome. I'll be limping mine along (bought 2005) for as long as possible.