I know it has been a while since I worked on this... We just moved and now that we are settled back in I can get this sorted out.
To set the stage here is the way I would describe a normal start up from a modern Mac laptop.
# Press the Power button
# The Apple appears with a spinning wheel
# The spinning wheel stops
# Split second of a blue screen
# The desktop appears
My tea-stained laptop
# Press the Power button
# The Apple appears with a spinning wheel
# The spinning wheel stops
# Split second of a blue screen
# All goes black
I connected the laptop to an external monitor (a projector) and had to restart as it did not recognize the projector.
# Press the Power button
# The Apple appears with a spinning wheel - through the projector only
# The spinning wheel stops - through the projector only
# Split second of a blue screen - through the projector only
# The desktop appears - through the projector only
The machine works!!
However, only through the projector.
It does not do any type of dual display(ing). Even the start-up items do not show up on the laptop's display.
I believe this is telling me that the laptop display does work as it displays up until showing the desktop.
It is in fact awake and functional once started, as seen through the projector.
So how can I get the laptop display to keep working past the start-up flow?
The link in the post above, regarding the ambient light sensor, mentions replacing or removing this sensor. However they are talking about a different model in that link. Can it still apply? Is it OK to just remove it? This is will not trigger some type of hardware warning/issue?
Thanks