I had no experience fixing a refrigerator, but I knew the problem was the door not closing. Suspecting that either the bottom hinge or the door gasket to be the problem, I decided to buy those parts from AppliancePartsPros to do the repair.
First, loosening the bolts, I took the door out. Afterwards, I checked the bottom hinge and discovered that the hinge pin was worn out. The gasket for the door was not in a good shape (lost some magnetic adherence in some spots and had some holes), so I decided to changed with the one I bought. Second, I changed the gasket in the door, following the easy instructions given by AppliancePartsPros in the delivery package. Third, I re-intalled the door in the refrigerator and checked with a thermometer the coldness inside the refrigerator. It was fine.
Once I finished the project, I treated myself to a glass of good and a sandwich, and I was still surprised how reasonably easy it was to do it.