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)

What do you mean by the words "the drive crashes" ?
And what method have you tried for formatting? I mean, have you tried several ways of formatting or just stick to the one ?
And what is "phase 3" ? 

Here is the discussion about that question: Format an encrypted drive
From that discussion i would say, that, first of all, determine how and where the encryption is implemented. Actually, i think that's the key point, as you'll know then what you are dealing with and what kind of tools you need to bypass the security. Can't tell more precisely, as I don't know the situation. 

BTW, is the drive internal or external ?

As long as it is software encryption...
1) fdisk
2) format