After Freddy malfunctions, you are left to find a Backstage Pass to help Freddy. This guide will show you where you can get the Backstage Pass and complete the mission in Rehearsal Space.
In the Level 2 area where Freddy malfunctions, you will find a sign on top of a door that says Backstage: Staff Only. Enter the door and follow the hallway until you reach another door with an Exit sign on top of it.
Enter this door and you will enter a huge with Security Bots lurking around. Keep going north, and you will see planks of wood stacked up together. There are tables and chairs in this area as well.
Keep going north until you reach an area that branches out to your right. There is another security bot here and you have to wait for it to turn around before you can continue on the hallway.
Hide in the trash bins to your right if you need to. Keep going north until you reach the end of the hallway. You will find a red door to your right.