2012 GMC Yukon Denali

KEY GETS STUCK IN THE IGNITION ALL THE TIME. THE TRUCK GOES INTO COMPLETE SHUT DOWN OF ALL ELECTRICAL COMPONENTS, I MEAN ABSOLUTELY NO POWER. I CAN'T EVEN CALL ON THE BLUE ON STAR BUTTON. I TOOK IT TO WALKER GMC IN ALEXANDRIA, LA ON JANUARY 15, 2018 BECAUSE THE ENGINE LIGHT WAS ON. THEY SAID THEY FIXED IT AND ALTHOUGH THE ENGINE LIGHT IS NO LONGER COMING ON, THE TRUCK CONTINUES TO GO INTO COMPLETE ELECTRICAL SHUT DOWN EVERY FEW DAYS. I TOOK IT TO ANOTHER DEALERSHIP TO TEST THE BATTERY AND THE ALTERNATOR BUT THEY REPORTED THE BATTERY WAS AT 100 PERCENT AND THE ALTERNATOR PASSED ALL THE CHECKS. I'M AT A LOST BUT I DO NOT WANT TO RISK TRAVELING WITH MY DAUGHTERS AND THE TRUCK JUST COMPLETELY STOPPING ON US ON THE HIGHWAY. WHAT DO YOU SUGGEST I DO NEXT?

I HAVE A 2012 GMC YUKON DENALI. I'VE HAD SEVERAL OCCASIONS WHERE I'M DRIVING AND THE TRUCK TURNS OFF/OR EXPERIENCES A "SHORT" FOR A FEW SECONDS. I HAVE CHECKED ALL ELECTRICAL CABLES AND HAVE EXCHANGED BATTERIES TWICE (AS THEY "DRAINED"). A FEW MONTHS BACK MY DASHBOARD STARTED CRACKING AS WELL, FIRST IT WAS A SMALL CRACK NEAR THE PASSENGER SIDE AIRBAG. LATER ANOTHER CRACK BY THE STEERING WHEEL, WHICH HAD NOW FORMED A LARGE "V".