How do you defeat ironhide on transformers decepticons?

As you know this is the last misson END GAME it has two parts
Part 1;you are playing as your own autobot Dodge all of megatrons attacks and get behind him.Hit him from behind(use the tricked out car in vehicle mode) you will have to do this 5 times
Then he will drop the all spark grab it and hit him with it
Part 2;once you hit him with the allspark the will be a cut scene after that you will be playing as optimus prime then it is good old fighting.