Get Even

For this achievement, simply replay the ADS Heist but do not kill any guards. The way I did this was as follows:

From the beginning, follow the path forward and then left. Go past the pipes and turn right. When you get to a turning (left/right), turn right and use your scanner on the pipes. This will remove them. Follow the path round until you get to the pipe puzzle. Turn the valves as required using the heat detection app on your phone until you can progress.

You will then go into a repetitive loop of opening doors and trying out the corner gun. Follow the corner gun tutorial until you exit the door and you will end up in the ADS building. THIS is where you need to be careful.

Open the door ahead of you and then crouch. You will need to stay crouched for the duration of this section. Wait until the guard moves forward a few steps and then move forward just past the car on your left and move all the way to the left. Follow the car park up, watching the guards carefully. Proceed into the next section of the car park once the guard has also moved into the next section of the car park and stay behind the first wall in front of you - you should have a guard that does not move on your left. Face left and use your scanner to scan 2 items in for cover. Move this way and then press the button on the wall - this will call the lift. Go into the lift and press the button.

When the doors open, move forward and then left towards the other lift entrance. Near here, you will see a guard in the middle of the room and you should be near a door. When the guard is looking in your direction, as soon as he turns around, crouch and move out of the door and up the stairs. Walk left and you should see another lift on your right. Enter here to go to the last floor with guards.

When you get here move forward and the guards will complain about the plumbing not working. At this point, if you haven't already unlocked it, you will earn this achievement:

Turn right into a room with several computers and a grate. Scan the grate to open it and walk through. You should see and hear a guard in front of you complaining about the vending machine. Wait until he moves away and through the door, then exit out of the door to your left and walk around to the lift, still crouching the whole time. Call the lift, get in and press the button before the guard detects you.

When you reach the top floor, the achievement should pop.