Kimberdawn

Hello. My first post. Hopefully others have had some experience to tell me the possibilities of what's up with my truck. Screen just went black a week ago. No sound from radio, blinkers, or door chimes. Checked fuses. Checked for a ground issue (we were lucky enough to obtain the electrical diagram) Checked the blue wire going into the HMI. Disconnected the battery. Tried pushing the button by the onstar. All no luck. Anyone else run into this issue?