So what do you think happened?
It's going to be tough to work that out with so little evidence, Founder, and I'm not going to pre-empt official findings, particularly given that the flight recorders have yet to be dragged from the depths.
There are presently no conclusions - there is no indication of the technical condition of the aircraft and its engines, there is no solid flight data from the aircraft itself, and only basic information acquired from radar data, communication records, and interviews with air traffic controllers and airport authorities.
But regarding the circumstances of the accident, I'll echo other posters' points regarding the similarity of those circumstances to the Gulf Air accident, also involving an A320, of August 2000.
Both involved the aircraft making a coastal approach, in darkness, and under testing conditions - the Armavia flight owing to the weather and the Gulf Air flight owing to an unstable approach.
Both attempts at landing were aborted with the crews turning the aircraft away from the approach centreline in a direction which took them over a expansive body of water - featureless terrain at the best of times, and in the dark especially difficult to use as a visual reference.
Without a visual reference, the ability to retain situational awareness of the aircraft's attitude, movement and position by ordinary sensory perception is seriously impeded - hence the importance of pilots' closely monitoring and trusting the information relayed by the aircraft's instrument panel.
Nothing above is intended as a conclusion, by any means, but the circumstances provide a timely reminder to a simple fact which has been demonstrated in aviation time and again: if the aircraft isn't doing what you think it's doing, or isn't where you think it is, then sooner or later there's going to be trouble.