Confused about Megatron's plan
(Critical spoiler follows): I'm confused as to what Megatron's plan was exactly. He says in this movie that he was heading to Earth to meet with a defecting Sentinel Prime who had the tech to resurrect Cybertron. However, it was established in the first movie and official tie-in stuff that Megatron went to Earth in search of the Cube. If he already knew about the tech Sentinel Prime was bringing, why did he need the cube? And I'm similarly confused about how The Fallen fits into Megatron's schemes with Sentinel Prime.