Hi 07mbe320!
Welcome to the forums and congrats on your first post! It definitely sounds like you have a starter issue. We have a lot of technical articles that I think you'll find extremely useful and very easy to follow. I've included a link to a tech article on starter issue in the W211. If you have any more questions about it, feel free to post a Comment just below the article and someone will get back to you with more tech. help.
Let me know if it's helpful to you and feel free to browse our other sections for more useful info on your W211. Best of luck!
Mercedes W211 Starter Issue Tech Article -
Mercedes-Benz W211 6-Cylinder Starter Replacement (2003-2009) E320 | Pelican Parts DIY Maintenance Article
-Dmitry