<< Solved >> macOS Doesn't Boot if HDMI is Connected to Internal Graphics!

[techana]

I was playing with HiDPI settings the other day and now my mackintosh doesn't boot if the HTMI cable is connected to the internal graphics chip (Intel UHD Graphics 630). The progress bar that appears under the Apple logo in the black startup screen stops at about 90% and stays there!

The machine only boots when the HDMI is connected to the external graphics card (Radeon RX 570).

I wonder how to reset the graphics system in order to resume Intel chip operation?

 

[techana]

It turned out that I put a wrong number in ig-platform-id. Once I put the right ID, the computer boots normally.