Yes the starter is in a normal location, but MB decided to put a shield under the engine. You will find out a starter is not cheap, the battery is under the carpet passenger side trunk, wheel well.
You are not going to be able to check the alternator it is really buried, I hate to say so see if there is a Mb dealer that can pull some codes. If it had no power it could be limp home, bad ign switch will cause no start, solenoid maybe, you got to get there by elimination. Here is some good reading
http://v12uberalles.com/