It's no clear to mean what you mean with "phase 3" and what you exactly want to achieve. If you want to format the drive and destroy all data on it, I don't see a problem, how are you trying to do it? Or what are the rules of the game? On the other hand, if what you're trying to do is recover the encryption key, then you'll have to invest a lot of time (and may not be successful), since you'll have to try to find a side-channel attack or some bug int the implementation of the cipher (finding theoretically a weakness in the cipher requires a lot, specially without the proper knowledge and experience)