Valpojim

I'm looking for someone who can tell me how I can check my backup camera. I own a 2014 Kia Forte LX. I was told by my dealer that my camera has gone bad. They proceeded to tell me it would cost just over $600 to replace it. I did a search on Kia parts and discovered I could buy one for $290. My thoughts are buy it. Then I thought maybe the technician who checked my camera could have misdiagnosed it. So can someone tell me how I can make sure it's bad?