Chevrolet Repair: 1985 GMC Electrical Problems, windshield wipers, aftermarket stereo

Question
I have an aftermarket stereo installed in my 1985 GMC.  I had a friend installing an amp for some additional speakers.  After everything was hooked up I had no power to my stereo.  He just unhooked everything he did and left it as it was before.  Now I still do not have power to my stereo, cigarette lighter.  Horn and windshield wipers do not work.  When I turn on my lights or windshield wipers the door buzzer stays on and it lights up the blinkers in the dash.  When lights are on I have no dashlights and gauges.  My dims are brights and my brights are dim.  He looked at my fuses and said they are all good.

Answer
HI JENNIFER, YOUR TRUCK SOUNDS POSSESSED,ONLY KIDDING. THIS IS A QUESTION WHERE I AM GOING TO JUST GUESS. I WOULD REALLY NEED TO SEE THIS AND DO SOME DIAGNOSTIC WORK ON IT. ARE YOU SURE HE CHECKED ALL THE FUSES AND ALL OF THEM ARE ALL OK ???? IS HE USING A TEST LIGHT TO CK THEM OR OHM METER ??? OR JUST LOOKING AT THEM, BECAUSE MOST OF YOUR PROBLEMS NOT ALL SOUND LIKE A BAD FUSE. IF ALL OF THE FUSES ARE OK I WOULD BE LOOKING INTO A FAULTY GROUND CIRCUIT..WHEN SOMETHING STRANGE HAPPENS LIKE THIS CK FOR GROUND PROBLEMS.CK THE SMALL WIRE COMING FROM THE NEG SIDE OF BATTERY GOING TO THE BODY GROUND,MAKE SURE IT IS CLEAN AND TIGHT..WITH ALL OF THESE PROBLEMS AFTER THE AMP WAS INSTALLED IT SOUNDS LIKE MAYBE SOMETHING SHORTED OUT CAUSING THIESE PROBLEMS. JENNIFER IF YOU CAN CK THE ABOVE SUGGESTIONS AND GET BACK TO ME WITH MORE INFO.I WOULD LIKE TO HELP YOU FURTHER. ALSO WHEN YOU LEAVE THIS SITE WOULD YOU PLEASE RATE MY ANSWER,THIS WILL HELP ME, THANKS TOM.