[Steve Van Doorn]

said, " it used to be during Reftra (refresher training assessment) on a ship one of the things they would do is eliminate all the electronics and force the crew to go back to basic manual things"

Though self steering systems are shut off when you want to steer it yourself. If it's hacked you can't shut it off. There was no actual over ride of the computer same with your car.
If the car computer goes down your car stops functioning. Likely how they saved many crashes. Simply shutting off the ships systems and drift. How they did this with a plane I don't know.

[reed13k]

If that’s true then it was a crappy design - fail safes should fail “safe” and allow manual override at all times not force you to accept whatever fate the system decides.