If the aircraft had been landed and shut down it would not have exhibited the degree of destruction evident from the wreckage.
It crashed vertically on to and through the roof with little or no NR, leaving an EC135 shaped hole with no evidence of forward speed. Why? None of us knows. The AAIB will hopefully work it out!
Edit: Agree Tandem. A May day would achieve nothing but distraction at a very busy time.