I have a story AS an overwhelmed newbie.
I'd worked at the same exact store in high school, four years previous. Because I was a returning cashier, and a fast learner, my boss decided to leave just me and his ten-year-old son alone at the store. This was so he cound run some errands (the son knows how to do just about everything, so this really isn't a big deal). However, it was only my fifth day.
Cut to me accidentally stopping all the gas pumps, while I've got a store full of customers. I sort of went into panic mode, and shouted up the stairs to the kid asking if he knows how to restart the gas pumps. When he didn't I then called my boss to fix it.
Lucky me, he was only a couple of miles away and on his way back in, it was an easy fix (though something that's hard to explain over the phone), and the vast majority of our customers are chill.
The only one that got annoyed was one lady that wanted gas, because she'd prepaid and thought we were trying to rip her off.