I would probably take it to dealer or an indy shop and let them diagnose it first and perhaps pick up some tips/ ideas from them and cost. Upon that information decide if want to do it yourself or not.
BTW, found this link if that helps any. Good Luck!
https://f30.bimmerpost.com/forums/sh....php?t=1663803
and this video starting @ 32:59 showing how to change solenoids, circuit board, etc. on BMW E70 X5. It is not the same but you will get the idea.