Close - based on GAL's original plan, as elaborated on by Richard Hatch in his novels, Iblis was once a member of the Beings of Light and they ousted him for being...well...bad. Out of revenge, he found this race of semi-sentient and
highly warlike reptiles hidden away near the Colonies and brought them the gift of hyper-advanced tech (which they obviously weren't ready for, ethically or emotionally). They of course embraced it, quickly borgified themselves and eventually made automatons that killed them off. In the original treatment, there were live aliens in the robot suits, but ABC nixed that because they didn't want to see the kids watching their heroes blowing away other living beings every Sunday night, so they went with the whole "evil robots overthrew their living masters centuries ago" trope.
Standard Centurions have one "brain". Gold Command Centurions and Lucifer/Spectre IL models have two "brains". When an Impy dies, an IL is promoted and it gets the unique "third brain", which is said to have been a piece of "divine" tech imbued with Iblis' essence, giving Impy his voice and, consequently, becoming Iblis' puppet, controlling the entire Cylon Alliance. This was all his plan to destroy the humans, whom he saw as the Seraphs' "pets" that were being helped along to ascension like they were. He was jealous of this and vowed revenge in this "cosmic chess game", with the humans and cylons being the pawns. The concept was wonderful, but the execution suffered horribly.

To think about what could have been...