THEORIES: 1.) KSI Technology. hence, "Transformium" or "part of it" got integrated to Bee's upgrade. (pulling parts together) Heck, Joshua Joyce is now allied with Cade and the Autobots. 2.) Headmaster Tech. Probably Cogman is driving Bee. Somehow Cogman's "spark" integrated with Bee's? Remember how Prime pulled Jetfire's parts? 3.) Michael Bay. Probably he did something "out of the TF lore" fans never know. 4.) Because there will be a Bee spin-off film. Bee must not die for future films.