suggest you read up on Aeroflot 821 and Tartastan 363 and to a lesser extent Thomson Airways at BOH and Turkish at AMS. The first two on the face of it look eerily similar to this incident. The other two can help your understanding as to what can go wrong whilst low and slow.
This flight was not low. Slow, yes, at some point that must have happened, but you don't climb 2500 ft if you are slow.
That takes time.
Normally, pilots screw up at low altitude, or when they are in transit from one flight phase to another.
It's weird to loose it after climbing 2500 ft, but this looks like the most likely scenario just now.