95 C280 wont start
how long did you let it charge after AAA jump started it? usually, an hour is a good rule of thumb to let it sit and charge.
it may be time to get a new battery if it can't hold the charge...
the security system must have read that i locked the car from the outside but i opened my door before it was locked. 
i doubt your's is something this simple but you never know.
but seriously, if the battery can't hold the charge after you jumped it, either it's too old and worn out, or you didn't let it charge long enough.
i don't think there are problems with electronics in the w202 draining the battery...atleast i haven't heard of any yet.



