Car Hifi PowerCap no longer works

Hello, I hope someone can help me, or at least give me one possible cause. The facts are this: Today at noon everything was supi, but tonight, after I tried other LS at the end socket, the PowerCap didn’t go on any more. So the volt indicator shows nothing more. Besides, a fieping in the vocals now arrives, which are connected to the end socket. If the level rule turns down at the end socket, until just below the half is the fieping away. It doesn’t come slow, but is either there in full volume or there is absolutely no. I’m desperate. Greetings