The probable cause of this major accident is a fatigued flight crew, who had received awful training on said type, flew into bad met. conditions and got either disoriented or did not follow standard procedure when it came to executing an instrument-related approach (i.e. CFIT).
How absurd can you be.
Obviously very little factual information is available, however if we take the statement that the co-pilot radioed a loss of control and the unusual speed and altitude it's just as likely that either windshear or structural damage (or both) led to an unrecoverable condition.