From the third floor office, Displace to the top of the elevator and then to the top of the shaft after opening the hatch. In the next room, you need to Displace to the room with the desk in it (past the arc Pylon) where you can grab a tool in the right drawer. Move quickly into the room to your left and save. Displace yourself into the hole in the floor, it will take a few tries. Once you are in there, drop down onto the vault and loosen all four brakes.