My car has a 6 disc with the sound system. Through the steering wheel controls, I can control the radio, but the push buttons that are directly on the radio do not work. That includes the power button - it doesn’t work directly on the radio either. However, the volume does work and also the turn dial does work to change the stations. What will fix this problem?
It sounds like the radio unit in your vehicle may have partially failed to where the controls no longer work. I would recommend having your radio inspected by a qualified professional. This inspection may involve the removal of the radio and some sort of bench testing with a high tech scan tool or machine of some kind that is used specifically for the testing of automotive radio equipment. This electrical inspection may also include using a digital multimeter to test certain wires that connect to your radio that may control the use of the buttons on the face of the radio. If the inspection shows that your radio controls have shorted out, replace the radio if necessary to regain this function in your vehicle.