New Stereo Receivers not working

I have a 1999 Lumina, and the stock radio started going out, so I first replaced it with a JVC CD receiver. Bought it from American, and had them install it. After a couple weeks, no sound came out at all, although the receiver appeared to be working. I took it back in, they said there was nothing wrong with the speakers, so they sent the receiver to the manufacturer, who said there was a problem with the amplifier, so they fixed it and installed again. Same thing happened again after a few days.

When I went back the 2nd time with the JVC, the installer said the receiver was "very hot (temperature)" when he removed it.

I thought it might be that particular receiver, so I got a credit and puchased a nicer Alpine unit. Two days after they installed it, same thing happened - no sound, even though the receiver was working.

I saw some other threads about making sure new receivers are grounded - not sure if that fits for this situation. Could something be running hot with my car's wiring to the new units? Or maybe the stock speakers have trouble with the new receivers?

Any other ideas? This is very frustrating - I've got to have my music!

Thanks for your help - -

Maybe something in the speed controlled volume system isn't hooked up correctly, they might have it overloading it somehow when the signal to inrease volume changes, and eventually the amp can't handle it?

Some of these have a remote amp, maybe the system impedance is wrong.