Seems like the button business from earlier is finally making sense. In this room, there’s four buttons you can press, a BLUE one, a YELLOW one, a GREEN one and a RED one.
You decide to press the BLUE button, as that’s what you heard was right.

You press the Blue Button. All the other buttons disappear and the room turns blue. Suddenly, the doors disappear, but a descending staircase appears in its place.
Seems like there is no option but PROCEED.