Can someone please explain what this F1 hotkey does? On pressing fn+F1, I get a blank (dark) screen for 1 second and then it goes back to normal (displays what was there before). It doesn't seem to be doing anything at all, at least in Ubuntu!
Can someone please explain what this F1 hotkey does?
It switches to Presentation mode. I would assume the Presentation mode only supports Windows and/or you don't have another monitor connected to your device.
Switch to another display mode when an external display is connected.
That key is used to switch between connected displays to the PC. I think the symptom you explained of black screen is because you do not have any external display connected to your pc.
Reference: Support HP Check the section titled Keys with icons or symbols.