My battery died. Caused several problems. Replaced with NEW battery, everything affected (I think) back to normal?

I bought car in 2020. Cruise control did not work at all at that time and person I bought car from didn't know anything. It was two years later that battery failed so I cannot confidently say the cruise control failed from that. Possibly previous failed battery with previous owner who knew nothing to begin with?

Could the cruise control have been disconnected and if so, is there any physical visual confirmation of such under the hood, or?

Please help. Thank you.

You could take a chance and just replace the module, but Mercedes parts are expensive and unless you can DIY the work, the labor will be costly. Before you take on that expense, I recommend that you bring the car to a shop that can scan the system with a Mercedes-compatible scan tool. The correct tool will be able to communicate with the cruise control module and precisely identify the problem.

My 2005 C230 has a minor issue with the cruise control. If I press hard on the lever, the system goes dead, and I can't use it until I re-start the car. I've learned to press the lever gently and maintain the function. When I scan my car, the system tells me that the signal from the cruise control is "implausible." I think I need to replace the module in order to clear up the problem. Unfortunately, that involves removing the steering wheel. I will probably get around to that someday.

Good luck.