Nexus 5 camera can’t focus after replace it


My Nexus 5 camera had small stains inside that can’t be cleaned. Apart from stains the camera was working correctly, taking photos and focusing.
Because of this problem I bought a new camera module and replaced it. Obviously stains disappeared, but now I have a problem with focus function. Close-up photos are always blurred, it’s imposible to focus.

I wiped data and cache from camera application, and tested it with android Lollipop 5.1.1 and KitKat 4.4.4 but the result is always the same. The outer lens housing is also perfectly clean.

Seller says that focus problem is not caused by the new camera because focus question should be done by the system.
What is your opinion? The problem is caused by camera module or not?