before you start pulling things apart, what's wrong with the receiver?
this looks like a Pioneer receiver. connector 1, put your index finger behind the cable and pull straight out with your thumb gripping the center of the cable. connector 2, which is a vertical PCB that mates with the main pcb, use a screwdriver very carefully to walk the vertical board away from the main board a little at a time, alternating ends of the connector. do not try tp pry the connector itself, they can be brittle. also the fulcrum you push against should be the main board, which is fiberglass and stronger, and the tip of the screwdriver pushing against the vertical board (which is made of "crackerboard", and breaks easily if you're not careful).