I had a partial black "oval" at the side of my Galaxy Note 9. Had to go through two (2) OLED replacements until they found one that worked.
It was not until several days later, however, that I tried to use the stylus.
The Note 9 recognizes when I remove/insert the stylus, and I can use the stylus button to take pictures, etc.
But I cannot use the stylus to write on the screen anymore.
The technician took it apart and made sure all of the connections were snug, but no joy. He is now ordering another screen to rule that out as the problem.
Any ideas on what else it could be?