Well, hopefully someone that has direct knowledge will chime in or might have better suggestions.

Again check the fuses/relays. Also, check the ECM box in the engine compartment for moisture.

Just some guesses but maybe check harness connections in the engine compartment - since you said it happened in the rain.

Another, is check to see if you might have a leaky sunroof cassette or clogged drains. Maybe you have some corrosion from moisture somewhere in the cabin.

If you do a search and can't find anything, I would just take it to a dealer or BMW shop. It will probably save you time and money in the long run, especially if its some kind of electrical gremlin. BMW diagnostics will give BMW specific codes instead of generic P codes which are not as helpful.

Right now, you (we) are just shooting in the dark.