The AD said to establish trim with the control wheel trim switches prior to shutting off the trim motors.
So they blew off step one. On a memory-item checklist; as is, learn it until they can do it in their dreams.
And they should not have gotten there as the pitch-power settings for instrument disagree would not have seen them retract the flaps in the first place, allowing MCAS to operate.
Those pilots took a compromised, but flyable situation and made sure it was deadly.
The FAA grounded it upon the realization that 3rd world pilots were not getting the correct training. Which Ethiopian Airlines was already well aware of when they put those pilots in that plane. ET was more concerned with the appearance of being a first rate operation and gaining praise for its amazing rapid expansion than it was interested in backing it with a dedication to safety.