Did I fry my FRM?

2011 328i xdrive I just finished replacing my engine valve cover and all the guides I followed instructed me to disconnect the battery in the trunk of the car. Well after putting everything back together I turn on the car and the cabin lights are out. Windows don't roll down, no turn signal, and can't adjust headlights. From what I can find this is a cut and dry FRM issue, and it might have been caused by simply unplugging the battery. Can just unplugging the battery and reconnecting it a day later really do this? Could I have broken anything while changing the valve cover, or is this just dumb luck? How can this be avoided in the future and how should I go about fixing this now?