i just bought a nitro head unit(BMW-4646MP) and cobbed the installlation just to see how it sounded. the head unit sounded great on my stock 92 firebird speakers.aafter a few days i noticed the left rear speaker stoped working so i took the radio out and tried to reconnect the wires. after doing so i had no sound at all. so i tried reconnecting all of the wires except the rear right front right and front left and still no sound. after playing with the sound i realized i can hear very little sound from the left rear speaker while turning the unit up to 35 volume when it goes up to 45(before 22 was pretty loud).

does this mean i've blown the speakers?

 

please can anyonw help me out?