I believe I covered that in one of my previous answers. I'll just summarize it again.
The ability for MCAS to fire has been protected. There are more inputs required than were in existence in the previous design. The system is only allowed to fire once per flight, where in the accident situations it was firing repeatedly. The authority that the MCAS has to drive the nose down has been scaled back such that, even if it did malfunction, it is now within the pilot's full ability to recover and overcome those aerodynamic forces.
There are comparative features or cross-checks between the two AOA sensors. If they're out by a certain difference between the two of them, it will kill the input and prevent the MCAS from firing. Finally, the electric trim switch on the control column, if applied by the pilot, will immediately engage the MCAS, which in the previous situation it did not.