No screen on my new Sony Stereo?

Hi, just got a sony stereo installed for a local car audio shop. All of a sudden the screen has stopped working. So the first thing i did is look online for any solutions. I found this car audio website http://how-to-install-car-audio-systems.blogspot.co.uk/2016/03/how-to-fix-no-screen-display-on-sony.html and i have cleaned the connectors and reset it just like it said and it came on for 5 seconds then it went back off again. Do you think the wires are loose or is it faulty, need your opinions guys thanks in advance.