If you recently updated your Mac Mini computer, or other Apple computer to 10.15.6 or some other version of macOS, you may notice that the HDMI port stops working.

Follow these steps to fix the problem:

  1. Power off the computer.
  2. Start the computer while holding command+option+p+r (the command key, the option key, and the letters P and R on the keyboard simultaneously).
  3. The computer should reset the hardware detection and on restarting again you can let go of the keys. The computer should start and the HDMI will likely work.

If this doesn’t help, you may need to pursue other diagnostic options.