The electric trim switches override MCAS. This was explained in the Emergency Airworthiness Directive sent to all MAX pilots after the first crash.

Also, overspeeding the airplane makes it much harder to turn the manual trim wheel. The cockpit voice recorder on the EA flight recorded the overspeed warning horn, which the crew did nothing about (they were at full power, should have pulled the throttles back).

The LA crew restored normal trim twenty-five times before crashing. What they never did was turn it off after restoring normal trim.