The standard answer is to stick a paper clip into the small hole to the lower right of the tray. My Xbox has a hole but there doesn’t seem to be a button in it. There is also no little hole underneath the ‘X’ or ‘O’ on the Xbox logo on the tray. I’m getting so frustrated I want to throw it against a wall.
The article is somewhat unclear, since what the paper clip pushes on is not really a button. The hole you found is almost certainly the correct one. The paper clip pushes on a lever that turns the tray opening gear train. Once you get the paper clip positioned in the hole you typically have to push in by about 5-10 mm. You will see the tray open slightly, after which you can pull it open with your fingers. You’ll want a somewhat stiff paper clip.