Backup Camera Turns On Randomly

Hello Everyone I've been reading through a lot of threads here and did a search but wasn't able to find an answer. I have a I have a 2010 Audi S4 with a NAV-TV unit that allows video and backup camera input to display on the factory nav screen. I also have an Alpine HCR-300r backup camera. Everything was installed by Best Buy and worked well at first. They also installed a relay, as that was required. However, a few months ago I developed a problem where the backup camera would occasionally toggle on while driving. The problem has become worse where it happens every time I drive. Sometimes, the camera is on when the car is turned on. Also, only once so far, the camera would turn on whenever I hit the brakes. Once it is toggled on, the NAV-TV input select button will not switch back to the normal screen. However, if I turn on my rear fog light, the backup camera will toggle off. Also, if I get out of my car while the camera is toggled on, and physically hit the top of my left trunk lid, it will also toggle off. Very strange. I already brought the car into Best Buy again and they checked all the wiring but it did not help. I do not believe this is a problem with the Alpine Camera or NAV-TV unit but thought that you guys might have some insight to help troubleshoot this issue. The other component that could be defective is the relay. Could that have this effect? Best Buy did not replace that yet. I asked this question to another installer and they suggested an improper ground. Does that seem likely? Thanks in advance! By the way, I'm not an installer/expert so I'll be bringing the back to Best Buy with suggestions.

I would check your ground wire from the camera to the reverse light ground. It is grounding out. also check to area where you bang, the wire may have gotten striped during install and or from opening and closing the trunk. If that checks out fine, replace the relay.The best tool in my work shop, is my BRAIN!!!!

Thanks krush.  Since Best Buy already looked at the wiring, I'm going to ask them to replace the relay.

Also, today as I was driving around, the camera would turn on everytime I hit the brakes.

I setup the appointment to have BB look at my issue and the tech said that the brake lights have nothing to do with the camera wiring. That was his response when I told him that my camera turns on when I step on the brake. I understand that the brakes are not directly connected to the camera but can someone explain to me how the brakes turn the camera on? Are you saying that "grounding out" causes the issue? Thanks!

So Best Buy replaced the relay and I assume they checked all the wiring again and the problems seems to be fixed.  Not sure if it was the relay or a bad ground.  Thanks for your replies.