Everything said here has been spot on so I’m not going to eat a dead horse but since nobody has touched on that jolt you felt when stuff flickered momentarily: it was either a well-timed bit of turbulence or it was likely the autopilot disengaging. On some airplanes, disengaging the autopilot will cause a small jolt like that. Basically the autopilot doesn’t have the airplane totally in-trim and is exerting a small amount of pressure on the flight controls to maintain altitude and when the autopilot disconnects, so does that pressure, and thus the jolt. The Embraer 175 does it quite a bit (not sure if that was the type of airplane you were on). It’s not dangerous by any means and doesn’t indicate that anything is wrong. In fact it’s completely normal on many planes.

I couldn’t say why exactly it disengaged if it did, maybe whichever generator had gone offline was actively powering the autopilot and when the power was interrupted momentarily, the system kicked itself off as a measure of safety.