You do have a multimeter so I would check the voltage right at the converter itself or where it enters your 12v fuse panel and see what you read. If you read 13.6 v or so your converter is functioning. If you are only reading 12.2v at the battery or 0v with the battery terminals disconnected then I would suspect a blown fuse or a break in the wires going to the battery. I assume your battery disconnect switch is on and your solenoids are working because you said your 120v plugs work and refer works. So what voltage reading do you get right at the converter?