Congratulations & welcome! I've been here on & (off lately) a few years, lots of smart, good folks here. My (common) experience; crankshaft position sensor failure & "relay control module" problems due to weak solder joints &/or relay failure. I'm no expert but not too difficult nor expensive for good d.i.y. person. I do not know about BCM & symptoms/remedies. I do know that water leaking into the "basement" of the trunk (under luggage area) can wreak havoc w/central locking control pump (a vacuum & electronic "module"). "Skreem" (security) "module" can be an issue, hope I/you never have to deal with that.
Folks here recommend finding a reputable independent German car repair specialist, if necessary, avoiding Dealers at all cost$. Your shop should have recorded trouble codes w/scanner, you might find translation for such codes here. Recommend you post symptoms & codes & best wishes going forward.
Our's is definitely a keeper.