Those older Jetliners were controlled by Hydraulics for commanding aero-surfaces.
The newer Jetliners are controlled by Electric Actuators and lots of Computer Systems. Too much in fact that the Aircraft does most of the work for the Flight Crew. No telling what was going on inside that Cockpit but, you can never have too much training for the Flight Crew in case the Computers completely fail.
In this case the Pitot Tube Froze (Airspeed Indicator Sensor) supplying this raw pressure data to the Flight Computer and converting it to scientific data so, Flight Crew can understand. Without the Airspeed the Computers SHUT DOWN all indicators. In other words all computer modules shut down and the Crew was left guessing. This is why I like the traditional gauges!!!
The Flight Crew that was in command of the Aircraft seems he did a fatal mistake to PULL BACK on the Yoke Stick as this rises the Nose of the Aircraft and increasing the Angle of attack. Going so Slow as this large and heavy Jetliner is, this caused the Aircraft to fall like a Rock as its wings no longer was carrying it's weight and thereby, no longer flying.
They hit the water at a very high Vertical rate of speed.