- We don't know if he meant the switch specifically at all. He could also have meant engines or thrust in general. There are many other visual signals and UX indicators to know if engines are spinning down. Thrust levels, to RPM to falling speed, change in angle of attack, rate of climb, even engine noise, vibrations you expect at full thrust etc.

- We also don't know if the switch was physically in cut off position in the first place or even if was the pilot noticed that specific visual signal and meant that when he spoke.

If it was a software issue, it is possible the switch was properly positioned, and software issue cut engine was cutoff, the display screens and other lights would show that.

In such a scenario, the pilot(s) would have likely checked with each other first if they did something as in the audio and manually tried restarting the engine as they seem to have done.

I am not saying it is a bug or any specific fault scenario, Just that it too early, we don't yet have enough information to say what is likely at all.