Friday evening I put my 2016 Chevy Silverado 2500 HD 4x4 Z71. 6.0 liter v-6 into gear. Upon starting the truck I received a check power steering system please drive safely message followed by a check trailer brake system. I had no reverse and no forward gears. This happened two more consecutive times. Truck is currently still at the dealership as they can’t find anything wrong. But are hoping to have the problem re-created so they can get to the bottom of it. Anybody have any idea why I would lose reverse and all drive gears. The truck threw 6 codes. One being lost communication with ECM. Any help would be greatly appreciative