I do not have an SEL but the SE has a "reset all back to factory" feature in the menu. Maybe give that a try.
On my 2009 E350, the drivers door stopped working out of nowhere 2 weeks ago. I can open ever other door no problem with the key in my pocket except the drivers door. It is driving me nuts (my girlfriend drives the E350 and uses the key, I use the SmartKey) because when I do drive it, I have to open and close the back door really quick in order to get into the front door. Anyone who watches probably thinks WTF is this dude doing?