After picking up the camera from the car and starting to walk, you'll see a small shed early on(first area after the car area) by the brook. Enter the cabin and go down the stairs. Interact with the door, then move back up and out of the shed - you'll hear the sound of a door opening.
Go back inside, down, and in through the door. Move further in and down until you get to the room with the circular hole in the middle. There is an electric panel on one of the columns by the wall: Flick all four switches there, then click the green button that lights up on the electrical equipment on the wall next to it.
There will be some additional lore relayed at this point, and the achievement should now unlock once you complete the game.