After you get through the Security Door, turn right and follow
the yellowy-green line to the Personal Facilities. When there press
the button in the room to the left and get into your Hazard Suit.
(See picture) Before you leave look in your locker and you will
find a Power Cell. Return the way you came and follow the blue line
to the level 3 security door and then go down the following lift
(elevator).
Follow the corridors until you get to the control room - here the
scientists will talk to you about the following procedure. (See
Picture) Walk over to the door and wait for the scientist to open
it, then make your way along the corridors, down the lift (elevator) and
then along the next corridor. Walk through the door marked test lab,
and you will find yourself in front of two scientists, who will talk
to each other about the procedure then open the door to the test
chamber.
When you enter the test chamber climb up the
ladder and wait for the flap covering the button to rise, then press
the button. Make your way back down the ladder and wait for the
carrier to arrive. When it does push it into the central section and
get ready for some fireworks. (See Picture) You will then be
teleported to some alien worlds before returning to Black Mesa,
where you find sirens wailing, and everything destroyed.