From my initial look at the report, looks like one or both of the above.Or the people that perform (or don't) the servicing and maintenance on the equipment.
Or (as in the case of the 737 Max) the pilots who don't RTFM.
FAA suggested that the locking mechanism on the switches needs regular maintenance checks. It was only advisory, so Air India apparently decided it wasn't worth the bother.
Then FO FUs and everything goes to brick.
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