2006 R500 (w251) electrical issues

I have a 2006 R500. The esp light has been intermittently coming on for about 2 months. Usually after driving, shut off, and driving again. It would come on right away for about 5 or 6 miles. The stereo also has been intermittently not working. The Nav works, but theres no audio. And the 6 disc changer in the glove box does not appear, nor does the satellite radio. Ok fast forward to 2 weeks ago. We got a ton of rain. After that the gremlins really came out. The dash was going nuts. I intermittent no starts. ESP light on fulltime. I went to pull the battery and the batt well had about 2 inches of water. Went forward of that under the passengers feet area where the electricals are and discovered the same. I removed the water, and thoroughly dried all components and cleaned with contact cleaner. Most of the gremlins have gone away. However the esp light remains on. And all taillights are out except the substitute bulbs and the third brake light. My question is this. Will the front sam do all this? Or should I be looking at the communication gateway? And where is the gateway located on my car? Will the front sam effect my stereo like that? Sorry for such a long post. I'm frustrated and can't find decent answers. And I love my R500! I want it back for out of town trips.

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