I had the battery out of my GT for over a week, and when I put a new battery in there were no noticeable problems at all.
You're golden there as I suspected. So now you can try undoing what you did prior to the problem arising, but my guess is that you have a wiped Body Control Module caused by something. May just have been a fluke........it happens, but usually as I mentioned beforehand, when something was fine before a change is made and not right afterward there is a strong possibility it contributed to or is the cause of the cropped up problem. Wish you luck. These S550's are making me rethink regressing to a 13/14 S197 or 03/04 SVT Cobra setup. I like gadgets.......up to a point.