holly-shmolly, dude!!!!!!!
did you ford some river????

the interconnections between the DSP, the NAV, the radio module and the phone module are in the sound wires, as those modules are powered via individual fused links...
So, one module going down would not necesseraly bring down the other modules, it may bring down an audio channel, but...

When you have water that will cause corrosion and possible short circuits, all bets are off, as those short circuits are not "pre-designed", they are random - you may have those modules killed independetly from each other... The Nav is sitting relatively high in the side of the trunk, and you need to fill the cabin with the water all the way up to the headrests to flood the Nav... the phone unit (is it a Bluetooth?), the DSP, the Radio, the PDC (you have PDC as seen on the picture), the tow module (if you have one) and the TV module are all sitting in "tub" environment and water can kill each one individually...

when electrical flow finds a new path due to a short, the X5 (and any other device) will act very strange - you may lose the turn signals, or, your fan can stay on all the time...

Disconnect the fuses for all the non-essential equipment (see the list i wrote above) by pulling the fuses (if you need the fuse info, check the WDS schematics), and see if any of your driving issues are resolved, or, if any NEW issues have manifested themselves...

For the contacts that are rusty... how good are you with electronics? What I would do in this case, I would take the connector apart, clean it up and replace each of the pins with a new one - they are NOT gold-plated, so they will corrode...

You can get the entirely new plastic connector from the dealer, probably about $10-15 for three piece connector - 61136920062, 61136909070 and the cap 61136920074. the terminals that you will need are either 61138369696 or 61138369700, or you can use terminals from Digi-Key.com, part # A28327-ND