I have a 2011 MBP17 and its on a third or fourth failed GPU. This time I have an external screen which gets a good signal so there is some sort of output but the main screen is totally non-functional.
I’ve had to replace the disk now too. I have a bootable installer on a USB drive for High Sierra.
The problem is that the installer and Recovery both want to put their windows on the original screen leaving me with a blank grey screen on the external monitor (with a functional pointer). Its clearly acting as an additional monitor as I can move the pointer off the left side of the screen as if there’s more screen space over there.
Is there any sequence of key strokes that I can use to do a fresh install of High Sierra without actually being able to see what I’m doing? Or some magic cheat code I can put in to force it to only consider the external monitor as existing (ie completely ignore the main MBP one)? Such things seem possible from within the OS with normal settings but I’m not at that point just yet.