O'Reilly Auto Parts review: Return-refund

I bought a remanufactured power steering pump and pressure hose for a 2009 Nissan Murano. I install the parts in my car but for reason the power steering pump start making loud noises, even worse than my original one. I took it out and decided to take it back, but the manager at the store said he can not take it back to do to me installing it in the first place. Now How do you know if the pump is good or bad without installing in the car to see if runs or not. In meanwhile I had to go to their competition to buy another pump to be able to go to work. I was trying to get my money back since they sold me a used pump that make no sense.