I can hear audio playing, but the screen is completely black. Anyone know how to fix?

I also got a black screen on startup. Then I started Fallout 4: Game of the Year Edition, set the resolution and quality in that little pop-up, exit, and started Fallout London again with no more black screens.

I confirm this as working for me. I had a similar issue. Fallout running in the background somewhere, with a completely wrong resolution after clicking play in the Fallout London launcher.

Thank you both. That worked.