Can't disable clamshell mode
I have a Macbook that I connected it to the computer and projector in an eclassroom. I thought I had set my laptop to mirror, but I think I accidentally set my laptop to be the external monitor. Now it won't turn on at all unless:
- it is connected to a the computer in the eclassroom (or probably any external monitor, but not sure; I'm using USBc to HDMI)
- my laptop is plugged in, even though I can see that it's fully charged.
Even then, I am required to use an external mouse and keyboard plugged into my laptop. My laptop screen stays black, but then I can use the external mouse and keyboard, and the screen projected to the external monitor to do stuff.
I have done some digging, and I am pretty sure that it's in Clamshell mode. The interwebz tell me that I can disable clamshell mode by going into Settings > Display > Arrange > untick mirroring. But I don't have those options. The options in Settings > Display (no arrange, no mirroring tick box - see below), and under the menu bar "Use as separate display" is checked, but I can't uncheck it (not shown).
Please help!
MacBook Pro 16″, macOS 10.15