I have a 300c (2007) its a long story with the same ending, I parked the car up for several months and the battery drained. I jump started it and it was fine except I now had three orange lights on, ABS, ESP/BAS and traction control.. I drove it for a few months like this till eventually giving it to a friend of my daughters garage to fix. Needless to say it sat in their yard for almost a year with nothing done to it. I finally got tired of chasing them and went and retrieved it myself. Lo & behold, not only do I still have all the lights on, it drove home in low gear pretty much the whole 7 miles home only changing up a gear very reluctantly when I was nearly home and wouldn't go above 30-35 mph.
The mechanic told me it had a error code u140e which he couldn't clear and that it would have to go to the dealers to have the ABS/ECU "reflashed" wit a "Starscan" device..
I'm now desperately seeking help and/or guidance