Mechanic Job in Plaquemine, Louisiana

Need diagnostics ran & problems repaired on 2016 GMC sierra 1500 Z71. Truck is broke down in plaquemine. Believe it is more than likely an electrical problem. Went from running fine to barely idling. Wouldn't get over 55mph, & wouldn't shift automatically. Had to use the manual shift. Once killed it wouldn't even turn over to crank back up. Received email from onstar saying starter motor was failing, or starter connection was bad. Then received another email saying that engine & transmission systems failing.