Answer:
The key to this riddle is realizing that you do not have to pull the emergency switch in the first
room, the entrance, and so that
room will not lock down. You can leave it, and then return to it and go out the other
door. And indeed this is exactly
what you need to do so you can hit all 16
rooms and end in the exit
room.
Once you know to leave and reenter the first
room, there are eight possible solutions to travel through all the
rooms and end at the exit. Because the first
room is clear, you can backtrack through it to get back on the right track and pull the emergency switch in every
room, saving the world from agonizing death by ancient virus.