If the wing was fully stalled at landing, the sink rate must have been extreme - about the same as with a parachute with area roughly equal to, or less than, the wing area - at least 1000 feet per minute, probably more, depending on the wing loading. If it was still in deep stall mode at ground contact, it must have hit the ground pretty hard, since power could not be used to horse the nose up and create upforce.

Very interesting - something that I have never seen, although I have made vertical landings with 3d-capable models by applying lots of power just before impact, and even then, only with some wind on the nose.