Lg wd door not unlocking

Hi I have a lg wd12124rd which will not unlock the door unless I unplug it, when I plug it back in it locks again. The machine works ie fills,empties and spins. I originally had to replace the handle and it worked fine when I tested it. I got a callback the next day and when I went back the interlock wouldn’t lock so I ordered one and replaced it today but now have the above problem. I found a wire had broken from heater, checked heater and disconnected just in case. I checked pressure system which was fine, so I am wondering if I have missed anything or if the PCB has blown? any advice would be really appreciated 🙂 thanks Peter