Just to confirm on this, do you get any video output if you test the system with no VGA display connected and using only HDMI? Are you able to get video on your system BIOS using only the HDMI display interface?
My apologies for the delayed response. No , I do not get video directly from the HDMI in POST or OS startup when removing VGA
Not having video on BIOS or out of the operating system environment, would indicate a hardware related problem.
You should try using another display, cable and check directly with your computer manufacturer to see if the hardware in the computer is working as normal.