Rear camera not focusing

So before I do a repair I try to test everything to see what is working or not. I tested both camera but did not take notice if the camera was auto focusing. This iphone 6 was dropped right on the corner directly above the rear camera and the screen cracked. After replacing the screen I discovered that the rear camera had a fixed focus of a subject that was close up and would not auto focus to an object in the distance. I looked at the customer's pictures to see if any of the recent photos were blurry but they were all clear. I'm not sure if this issue was caused by the customer dropping it or from my repair. Anybody have this issue?

What do you think can be done to resolve it? Could it be as easy as just a rear camera replacement or something with the board? I'm gonna buy a new rear camera go from there. What do you guys think?