Amp turns on and stays on but no sound

are you shure you not connect the amplifier in a wrong connection ...B+,GND,ACC.....ok...then checkif the speakers wires stay in good condicions, some times when we intalled the spk wires for the border of the doors a few times skrewered too.check if it hapen.
another ....check if the terminal spk is not going at ground whit the chasis
another to....4 ohms per channel ,anny voice coil spk burned...in short.
good look.