Skoda Superb MkIII 66304 car error

Hi, I have a problem with our Superb, the Ignition doesn’t work, it won’t even start or show anything on dashboard, it’s like that the car is dead. I changed the start button, I also changed the gateway unit, coded it and it shows the 66304 error code. What to do? Vcds almost didn’t work, until I tried the automatic test. Any solutions? I saw that someone had same problem and it was because of the towing device, could it be also because of it?