Yeah it’s definitely not an elegant solution, but it works for now. But I think I will fix it properly at some point, now that I know what the problem is.

You were absolutely correct. It was the ribbon cable. But the fault was so small I couldn’t see it with my aging eyes. But under magnification it was quite clear.

I am also coming to that conclusion. Which sucks because I have to take out the screen to replace it.

And yes. I’m sure I bought the right one :) I didn’t mention it in the original post, but I was aware of the different models and revisions.

Yes the speakers still work. And I can change the volume both in Big Picture mode and Desktop mode with the slider.

I don’t really know what to do in alsamixer to test/change volume input.

xev also doesn’t give any output when pressing the volume buttons.