Have lit up all the blue braziers in 2, 3 and secret rooms
But the last gate on the opening room is still blocked shut
Map 5-3 is for that gate, have you done that properly?
Did you use the last switch?
In addition to what MadameCurie & gamemaster posted above.
If you get stuck again check out the relevant Wiki pages, quests, maps, videos, guides, walkthroughs & hidden gifts