As I have put a more detailed post in the takara mp-11T thread I'll keep this brief. The piece that the head sits on is back to front meaning to transform him you have to remove the head then put it back on after.

Personally I believe this is rubbish coming from tt but at least it's not broken and I have zero plans to sell him and he will stay in bot mode so not a big issue for me. The next mp I get better exceed my expectations. ( hmm didn't end up being brief did it)