maybe i'm not complety right. Because mk4 is vdo based computer.
And vdo had that problem with touching the eject button.

So i don't know where you have look for your 2 times 12V.

But maybe you first can check your fuses from the ignition.
or maybe your radio must give that 12V i don't know.

But it's a first step to help......
So maybe someone else could help you now or can look at his unit......
So hopefully you can see the difference!

good luck!