Ok yep sounds a lot like "I am Galvatron!" to me, as I said I couldn't remember lol.
Well another idea is that tfwiki says Galvatron is a sparkless clone of Megatron and not the "real" Megatron so maybe this clone rescues his other self in between the two movies and helps him rebuild his body?
But yeah it is a Bay movie so probably better to just ignore continuity issues like this because BAYPLOSIONS! and ~jokes about balls/weed/human mating rituals!~