Not to forget, the same problem has happened before with aircraft pilots.

Someone doesn't notice that the the wrong engines are running, or someone forgot to power down one of the engines.

Or there was an engine failure. And in the confusion, someone powers down the wrong engines.

Usually in these cases, fatigue or information overload is a major factor.

The pilots were fully qualified. They were simply overworked, and too tired to realize their mistake.

I wouldn't assign all the blame to lack of training. The navy is very famously overworked and understaffed, and not just in the USA.