When you spawn in, immediately start moving the boxes to the right of the desk so they don't cover the slide puzzle on the wall. Complete the slide puzzle by following the directions below.

Up Left Down Left Up Right Up Left Down Down Right Up Right Down Left

Open and go through the door that opened to your left, follow the path down and crouch to go through the gap. Turn right and turn on the lights by finding the glowing red button. Go to the wall with three dials on it and input 87, 67, & 89. Input the code 741329 and hit the button that appears to the left. Walk through the door, making sure to hit the glowing green button on the wall to make the descent faster. Walk behind the the elevator and press the button. Turn off the conveyor belt and jump onto the railings closest to the belt Line up with the center of the wall to get past the elevator.