This bulletin notes that electric stabilizer can be used to neutralize the control column prior to STAB CUTOUT, which it appears the Ethiopian crew did not do.
The bulletin completely fails to note that if you don't time the STAB CUTOUT immediately after you use manual electronic control but instead the MCAS acts again before you cutout, you're left trying to manually trim the stabilizers in a situation where the elevators are putting so much force on the jackscrew that manual stabilizer trim may be impossible.
Appears? Where are you reading this to come to that conclusion?
Page 11 of the preliminary report, 05:40:35 "stab trim cut-out".
Page 26, five manual trim up inputs before that time. Manual trim is electric trim instigated with yoke toggle switch.
What is not certain (to me) is if continuous nose up toggle for sure would have inhibited the automatic nose down from MCAS shown at 05:40:45. It really looks like pitch trim still needed to come up more in order to relieve the control column force to bring it back to neutral.
Why didn't they continue to manually trim (electric) after 05:40:35 to relieve yoke back pressure and also to improve climb rate and also reduce speed? I suspect they actually got ahead of themselves, setting trim stab cutoff too soon, not realizing how much more insideous the MCAS upset case is compared to runaway stabilizer trim.
And that is the problem with no training. They had no way to iterate various scenarios of working and failed MCAS behaviors.
It seems the "yo-yo manoeuvre" required to manually trim when severely mistrimmed with deflected elevator stopped being taught or mentioned in Boeing manuals decades ago.
http://www.avioesemusicas.com/wp-content/uploads/2018/10/TBC...
And the FAA made it an emergency airworthiness directive in response.
The steps on it were broadly followed by the Ethiopian flight.