In the wrong for contacting HR?

A person I know has been asking if they were in the wrong for calling HR, and honestly I'm wondering the same thing.

So the thing is a friend of mine has been working at this fast food joint for a month and has had no problems at work until recently. Saturday was a really busy day and they were bombarded with hella orders to the point to where things were getting a little frustrating. Other workers in the kitchen chimed in to help. They said the kitchen was pretty chaotic it was unbelievable.

Anyway, the manager said they were fired because she said my friend was expected to work the grill alone. Needless to say my friend called HR afterward and thought it was bullshit they would be fired for that.

But I'm conflicted, I'm not really sure who was in the wrong here. Was the manager in the wrong for firing them or was my friend in the wrong because they did get some of the orders wrong although they were under a lot of pressure.

But what do y'all think?