Have a 2020 Denali HD. Just happened. Same thing check ecm check fuel check power steering etc. Fooled with if for twenty minutes then pulled fuse 78 for the ECM replaced it and fired right up. Took it to dealer can diagnose anything Mine was on of the first built ordered it the day orders opened. Also have had rear window replaced back carpet and rear seat because of a leak. Also had a problem with steering like many on this forum. I took it to my tire guy he found two tires were defective. Dealer replaced them steering problems were gone.
Have a 2020 Denali HD. Just happened. Same thing check ecm check fuel check power steering etc. Fooled with if for twenty minutes then pulled fuse 78 for the ECM replaced it and fired right up. Took it to dealer can diagnose anything Mine was on of the first built ordered it the day orders opened. Also have had rear window replaced back carpet and rear seat because of a leak. Also had a problem with steering like many on this forum. I took it to my tire guy he found two tires were defective. Dealer replaced them steering problems were gone.