What should i do about my Cockatiel?

My Cockatiel is called Ollie and he is brilliant and so clever.. ive had him since he was 3 months from a hand rearing breeder so he is well and truly tame. I decided to not clip his wings.. and he has adapted very well to my house and doesn't put himself in danger, the only thing is that this makes it difficult to get him back in his cage... so we found a hand sized mirror, which we have been using to attract his attention long enough to get him in his cage.. which has worked a treat because obviously they love their own reflection, but he has very quickly become very aggressive.. and has cleverly seeked out all the mirrors in the lower part of my house.. and become obsessed with them.. when i stop him from getting to his mirrors.. he screams over and over again... and when i try to play with him or tickle his.. he attacks my hands.. he has also become very aggressive when just passing his cage when hes in it.. he runs after you like a guard dog. i don't know what to do! as he has no mirrors in his cage to avoid this from happening.. but just from a small amount of interaction with a mirror.. he has become Mr Hyde! what should i do? i have stopped using the hand mirror and moved all other mirrors from his sight... help!