Before attempting to take the SCION, move into the large opening overlooking the TALL ROOM WITH LEDGES ABOVE THE LAVA POOL.
Jump down onto the big platform and head for the small, square door on the wall to the right.
It opens as you approach. Take a standing jump with Action to cross the gap and land in the opening...
...unlocking the "Secret Door" achievement/trophy. ("It's not [the] right time to be here. There's a door for you.")
Either reload that last save or follow the passageway and climb up into the doorway...
...to emerge in the DRAWBRIDGE ROOM. You'll then have to repeat the timed run to get back into the SCION ROOM.
DARK MODE: Even with brightness adjusted, dark images on a light background can be hard to see. May I suggest a reputable dark mode browser extension, such as Dark Reader? (Download only from trusted sites, like darkreader.org or your browser's web store.)
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