Kp123
A most hearty
to TechSurvivors. Sorry we could not have met under better circumstances.
Now, to the issue—
Some thoughts (guesses and musings):
1. As some display settings are stored in PRAM, you might try
Zapping the PRAM2. If you can, do a SafeBoot (restarting while holding the Shift key).
3. Without a display, how are you certain your machine is booting properly?
4. Have you tried using your display with a different computer? Results? And, have you tried a different display/monitor with your machine? Results?
5. How was it determined that you have a bad video card?
Also, please advise what size Studio Display you have and what OS you are using.
Even if the above brings you no joy, hang in there. Indeed there are folks about who do have the expertise you seek.