One of the first tasks you will need to complete is following the mysterious computer’s instructions by opening a door and finding a body. This will need to be done shortly after you arrive at The Flat. The first thing you should know is that the door in question is a secret door hidden behind a bookcase in the computer-filled room that will open after you arrive at The Flat.
How to open the door in The Flat
When you walk into the room, you will notice a row of glowing sockets in front of you. Each one of these will require a battery. Your first battery is actually just beside you, to the right.
Beside you, you will notice a table in the middle of the room. Atop the table is a glowing screen, and just to the left of that is a battery. Interact with the battery to pull it out, then place it in the first socket. Now, go to the right side of the room, and you will see a switch.
Pull the switch, and you will see the glowing screen beside it start moving to the left. Grab the battery out of the bottom of it and take it over and place it in the second wall socket.
Once it is in place, return to the console that moved and jump up on top of it. From there, jump to the top of the shelf. Up there, you will find the third battery. Pull it from the wall, then drop down and place it in the third socket.
Now it is time to make your way to the left side of the room. Here, you will find a stool. Jump on top of it and then up onto the shelves. Make your way to the right, and you will find the last battery. Take it to the fourth slot, and then a secret door in the shelves will open up.
Head inside, and you will discover a room with a robot body and some kind of pod in it. This is actually a red herring and is not the body that you seek. Jump onto the chair beside the body, then to the top of the pod, and finally to the shelves on the left. Go to the end and knock the box, and a small drone will fall out.
Now, bring the drone to the main console that you powered up, jump up to the desk, and place it in the strange box-like device on the table.