Keep reporting it to your dealer, unfortunately. Establishing a history is important because if they can't/won't fix the car, you may need to lemon law it to get a replacement Bolt or perhaps buy another car.
Because IMO this may well end up being a personal safety issue, I'll yet again make the point.
Trying to reproduce an intermittent error may be dealership SOP under normal conditions but this error, if accurate, strongly suggests your vehicle was assembled incorrectly and may have a mixture of components that were never intended to work properly together.
Since the software in this vehicle controls nearly everything, how can basic acceleration/braking/battery control systems be trusted?
Your dealer Bolt mechanic sounds out of his depth on this one, and would be well-advised to talk to Mama.