As Iron Man, fly up to the roof of the Mansion and start fixing.
When that's complete, interact with the console to the right. As you did in the vaults of Attilan, ignore the numbers and match the directional arrows when they flash to activate this one.
This causes to device to blow up. You can rebuild it almost immediately with the debris, but it'll be missing one piece. Before you hunt after it, smash the crates on the roof and build a second machine from the pieces.
Find your lost piece just over the roof's edge on the frontside of the mansion.
This last bit of assembly summons Strange, and activates the mission proper.