Grimrock

That sneaky little wall button...That would be it then, yes! Thank goodness, I thought my game had been glitched. every other playthrough and guide had no mention of the door closing again!

Alright, so I used the ornate key to open the door to the "III, II, I, III" puzzle, fought the fire guys, got through and finished the next puzzle, got the next key and the valor armour, so now what do I do? The door's closed when I got back, and I don't see any way to open it, so is there...