I need more info. Did you check the ground wire to make sure you have a good ground? Some installers try to rely on the antenna for a ground when hooking it up due to laziness and it will eventually burn the stereo out from low voltage, or, you could have amps that are killing the battery enough to drop the voltage down and it's killing the stereo. I have also seen ground loops kill stereos, but, I need a bit clearer info as to exactly whats happening to answer the question.
If it is a newer tv there will be hdmi hook ups and look what port it is in and using your remote find the input button and select the right hdmi port hope this helps Merry Christmas
