2012 R56 JCW (USA)

Yesterday, we had a couple inches of snow (also a couple inches the previous week and frequent precipitation the last few weeks) and my left low beam headlight was on for at least four hours according to my roommate. To be clear, this is the first time this has happened in the two years I've owned the car. I turned on the car, checked that the headlights and fog lights were in the off positions as well as checked the high beam. Turning indicators were not on either. I turned the car on and off multiple times. I ended up disconnecting the negative terminal of my battery last night and reconnected it this morning. I took out the fuses this morning, however they look fine. I haven't checked the relays. Do I need to replace the bulb, headlight, or the electrical harness for the headlight? Has anyone had this happen before? If so, what fixed your issue? I saw some posts saying that others who had similar issues had to replace their footwell modules as it had shorted out.

Edit: The car had not been driven for two weeks when this happened, so I'm inclined to say it had something to do with the snow/precipitation.