I had the same problem once. Put the BIOS jumper into Configuration mode. See manual for more information.
Thanks to the many, many of you who looked at my problem and especially to odakim who suggested the solution. The solution was to move the BIOS CNFG jumper from "normal" position 1-2 to 2-3. This caused my PC to go to the Configure mode. This displayed the BIOS update screen. I could then go to the VIDEO configuration and Change the IDG PRIMARY VIDEO PORT option back to AUTO. Then I put the jumper back to "normal" position 1-2. Then the PC would start normally displaying bios controlled text inviting me to load the operating system.
Since my monitor would not display, this was a very frustrating problem leaving me blind to a remedy. Again, thanks so much.