Sometimes screen remains black after boot sequence (A04 standard OS image)

That was the idea, but if you have verified that it’s up and running, maybe a better idea would be to ssh into it and try to tweak the backlight yourself.

If turning the backlight on manually via ssh fixes it, then maybe setting a cron job or tacking something onto the end of the init code would work. It might be the case that the display (or something between the board and the display) is a little balky after enough time and it isn’t ready when asked to turn on.