You typed "Nor..." — did you mean (the giant robot), or something like North (a location)? Or were you about to type a character name (e.g., Norm , Doofenshmirtz , Perry )?
This is the film's climax where the kids of Danville use Phineas and Ferb's past inventions to battle the invading Norm Bot army. Performed by the band Love Händel. Highlight:
Phineas and Ferb: Across the 2nd Dimension - Figure/Cheat Guide
They are eventually defeated when Doofenshmirtz-1 gives Doofenshmirtz-2 a toy train, resolving his childhood trauma and leading him to self-destruct the entire robot army. Giant Norm (Video Game Boss) Phineas and Ferb: Across the 2nd Dimension video game, there is a specific encounter with a Giant Norm The Robot Factory level. The gang is saved from being squashed by Giant Norm