2002 Mercedes Benz C240 battery

is engine cranking over or do you just get clicking when turning key?

if clicking, need to have your starter tested. if crank but no start, check spark at the plugs and ensure fuel pressure is correct.

It will start if I jump it. So I do not think it is the starter

Okay, since it drove for a week on the new battery, it seems as if the alternator is actually at fault. If the alternator is weak it will not charge the battery properly, meaning that the vehicle will use the battery to run on. The battery will then drain dead within a few days. I suggest having the alternator tested to ensure it is charging properly.

Thank you. Would the in dash computer show a charging problem is it was not charging?

Most likely not until the battery is almost drained.

It clicks, but If I jump it starts rightup. It does not say Undervoltage or any charging/battery problem on the dash computer

most part stores will test your charging system for free. let me know how the test results read out.

I believe I may have a similar problem. See my question under subject "Mercedes Benz C240 Battery or Alternator". Was it the Alternator in your case? If not, what was the root cause?