Bought a W211 AMG E55 05 with problems.

I just got an E55 AMG from 2005 a week or so ago. The seller notified me that the battery is bad. I had the battery tested and it’s not bad. But it gives me a red pop up warning in the instrument cluster that says “service battery, conven functions temporarily disabled” then my AC will shut off and turn back on 15 or so seconds later once the message disappears. Then it comes back on some time later. I noticed it doesn’t happen when I’m on the road and not stopping like highway driving, but if I’m stuck at a light or in a drive thru it pops up.

Secondly. I left the headlights on for like half an hour, I know it has an auto feature, but it was accident. when I started the car after shutting them off and my head unit wouldn’t turn on. I’ll press power and the MB logo illuminates but then goes away after about 30 seconds oppose the the usual 2, and instead of turning on it just goes black. I know it’s not the command unit.

And lastly, the airmatic suspension. The owner notified me that the car has an air leak. He said that it’s in the rear only and it’s the rear passenger airbag. The whole rear end sags tho, and also he said he got a regular shock from a junk yard and replaced the rear passenger one because the airmatic suspension breaks often. That can’t be good for the torque, speed, drifting, and burnouts, and cornering I’m doing with this car. To have one wheel that has completely different suspension characteristics than the rest can’t be good. I can feel that it corners very unstable when turning left. It must have something to do with that junk yard shock.

I’m not mechanical inclined, and owning a AMG MB when you’re not mechanically inclined, and also don’t have loads of cash can be difficult. I already have high ass insurance, and gas cost. But that’s why I turn to BenzWorld for answers. Maybe someone out there knows something about my battery or stereo issues that won’t run me up thousands when serviced at an MB center.