It would be interesting if any of the residents come forward to say if they’ve ever gone to the wrong door. That should be something her attorney should investigate.
When you are in a building that is designed exactly the same floor to floor, it is easy to do. I’ve spend all of my working my years [I’m 70 now] in skyscraper office buildings with exactly the same design on each floor.
It is easy to do. You do NOT HAVE TO BE DRUNK. You are essentially on auto-pilot, glancing at familiar points.
Having said that, I don’t have any idea what happened in this case.