What to do during the manual override procedure in Hitman 2
When you access the server room for the first time in How the Mighty Fall, you are tasked with pulling one of the server racks in an attempt to gain access.
No matter which of the four you pick in the servers in the room, an alarm will trip. Don't worry, it's all part of the story. Now hide on the outside of one of the server banks, as the guards which enter will only go as far as the middle of the room before leaving.
Once they have left, you must get a keycard. Exit through the other door in the server room - which is easily missed - to come to a corridor with two cleaners.