On our last run here (Timed out on the boss), we started killing the chariot with a couple gears still up. After that, we started killing the reamining gears (a single and a triple). BEFORE the last Archaic gears was defeated, I was able to open the door to the teleporter. Every resource I read says you need to clear the entire main room to open the door. Do you only need to kill the chariot? I'm 100% certain the last mob was not dead before I opened the door.
XI Wiki

