Software?

I know it's a ridiculous question given that this is a kids movie, but are these robots sustained by magic or something? No one ever mentions software, the entire movie is about hardware upgrades.

A theory can be that all of their bodies are made of a nano metric material which stores the robots identity and memories, that why when a "male" robot puts of "female" robot's legs, he starts walking and even behaving like a female robot; and could explain why a severed head can call and direct its body.