New firmware=No Picture

When I switched on my Live+ it told me new firmware was available. I should have known better than to download it but I did anyway. I now have no picture. I can’t roll back since I can see my screen to do anything. What now??

I decided to pull the power plug, wait an little, and plug it back in. That seems to have cured the problem, at least for now. Who knows what else is lurking in the background.