2011 Ford Mustang electrical system problems

After several miles uphill, the vehicle had begun to travel downhill. After less than one mile, the steering was unresponsive; driver's input assumed hydraulic response. There was none. The vehicle hit the side of a mountain; very narrow shoulder didn't allow for error. The car overturned. The 'black box' located in the steering wheel collects a volume of data except one important fact: steering wheel angle. The steering wheel was positioned to miss the mountain but not to enter the on-coming lane.

Electrical system problem. There does not seem to be a trigger in regard to rain, hot, or cold weather conditions or how it is being driven. I have had a ford dealership work on this to no avail. I will start with the safety aspect that is affected. It will do all of these things at once and then slowly come back online, sometimes the errors do not correct themselves. 1. No brake lights 2. No rear turn signal 3. No heat/air (it will turn on and off) - which is bad in inclement weather for old people 4.