Hi,
I make my way up to exactly the same point und ran crazy by troubleshooting.
In one situation I managed finally to install Sierra without IntelHD-GFX and activated remotedesktop for further inspections. I "repaired" the gfx patches, logged in from another mac and saw successfully loaded intelhd-kext!?
The next thing I recognized, was that closing the lid and open it after some seconds to force the screen to sleep, I got a clear desktop
Now I stuck with faulty energy savings, missing audio and shutdown crashes - some more things to fix on my side...
