Not trying to make this all about NAPA and returns but you often get better treatment if you are a regular customer.
I can return almost anything at the two stores I buy from...but O'Reilly's? Not a chance. Since they are the highest priced in town they seldom see me.
Most stores around here also do not take back any electrical returns.. starters, alternators, ignition, etc. You own it once you bought it. But, again, I can get away with a better deal as can most shops and repair guys.
Good luck on your swap...