No change for me neither with FB07. Don't know where to look now...
EDIT : i bet you already looked at that but i tried to figure what's changing between the black screen state and working screen state. So i recorded an ioreg while in black screen state (using VNC) with Auto-Update Off and compared to ioreg when the screen has started.
-I can see in ioreg with screen ON the value brightness changing when using the slider in SysPrefs in 4 lines under AppleBacklightDisplay>IODisplayParameters ("brightness", "brightness-probe", "linear-brightness" and "linear-brightness-probe")
-I noticed in the recorded ioreg for screen OFF that the "brightness" and "linear-brightess" values are at maximum (0x400), but the "brightness-probe" and "linear-brightness-probe" are stuck at 0x0
-These 2 values change to 0x400 (maximum) when the screen actually starts.
And don't know what the "probe" refers to. Maybe it's just the "answer" value the OS is getting back from the display.
Not sure if this could help but at least it confirms it seems to be a brightness issue.
I don't know if the solution would be to force this brightness-probe value at start with some patching. Or if this could be solved by having the NVRam fully working, and thus automatically setting back this value at boot.
Back to the beginning...