Ok, did some further searching now that i knew a bit better what to look for. And it turns out, as so often, I am not the first one with this issue. Here’s how to fix it, and it works, I created a file with just “576cvbs” in it, and now I have picture from the AV out.
Funny though that the splash screens work and then turns black. Well well, it works now, that’s great! 