What just happened ? Belt squeal and charging full?
I hope you didn't cause a short somewhere.......
As above check VR wiring and ground.
It might just be "coincidence" that something happened. Maybe the brushes are sticky, worn, and it wasn't charging for a few minutes, "you didn't notice that". Very hard to say, unless you can catch it again.
If it happens again, I would unplug the VR and nurse it home. If you are not using the lights, and not starting the engine 'a bunch' then it should run a long long ways on "just the battery"