MCAS was designed to over ride their elevator demand actions
Nope.
MCAS was designed to compensate for the nose up pitch caused by the engines on the 737 MAX.
All it checks is the angle of attack, whether the autopilot is on, whether the flaps are extended, and whether the engines are above a certain level of thrust. MCAS uses trim to control the pitch. The elevators are still under the control of the pilots.