I have a strange error. My laptop only works if the HDMI is connected to a television (didn't try VGA/monitor but I guess is the same).
If I start the laptop disconnected the screen is black, but works if I plug the cable. I tried with the fn key, but doesn't work either.
The laptop is an Acer Aspire 5552 Series with Windows 10. Tried to upgrade to Anniversary Edition to see if was a W10 issue, but the problem persist.