I installed a new Retro sound model one radio in my 70 big block Camaro. One wire from the fuse panel acc, one from the fuse panel bat, and one to ground. The radio worked for a week and then died and will not power on. I returned it to retrosound and they sent me a new radio. I tested the power wires from the fuse panel with a volt meter and they are providing the correct power. The new radio powered up and worked for a week and then it died. In both cases after the radios died they would sometimes turn on for about 10 seconds and then die. What the heck is going on? All my connections are good.