At the main menu click Freeplay and then do Mira HQ.
As soon as the game loads go to the Laptop, open the Laptop and click on Imposter.
As soon as you close the menu open up the sabotage menu and turn off the lights in the office. Walk north to the vent and go North and then East to the office.
Turn on the lights and sabotage fixed.
You can also kill Black in admin when the lights are out for another achievement.
You do need to load into an online game once and then back out before going to Freeplay.