I recently had my floors refinished as I'm about to sell me house. After having this done I had the bathroom resurfaced and the windows cleaned. Evidently someone had a spill of some type of caustic liquid as there is an approximate 2 1/2" area where the poly has been eaten away.
This is in a hallway that connects to four other rooms. Can this one area be repaired or do I need to have whole areas redone?

Call a floor contractor and have them look at the job. They may be able to sand
a small area and finish it to look similar to the rest of the hall and blend it in. It depends on where the area is located. It may take several trips to get the job done.
It would help to know exactly what type and brand of finish that was used.
Taping off the area and using a scraper then sand paper would be my choice.