Here is a guide on how to find hidden console that allows you to play Eletris!
How to find console
Then go to the room where you place all computers.
Take the console from inside the drawer.
Go back to your office and you’ll have a job to repair it.
When repaired, before sending it back you can click into it and play Eletris.
Thanks to speaks for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.