Leaky roof following complete roof replacement

Looking for your input regarding any experience with the following situation:

I replaced a roof on a property of mine in Vegas last year . This year the roof leaked again, so we had the roofer go again and make repairs, since the roof was still under warranty. The roofer claims repairs were completed.

I was thinking of getting an independent roof inspection done to ensure that all necessary repairs were completed. My question is: how to I approach the roofer who completed repairs if anything comes up on the inspection report? Do I have the PM send him the inspection and tell them to complete repairs? Do I have a lawyer write something up and send to them? Thank you in advance!