Electrical Problem with 1995 Mercedes C220

I have a 1995 Mercedes C220. I am having an electrical problem, I think. It is my second car so I often let it sit unused for weeks at a time. Recently when I went to start it, it was completely dead, not even a click. So I gave it a jump. But, when I went back to drive it, the check engine light was on and the radio no longer worked, the radio just said “Code” and the C was flashing. Then the turn signal clicker started going on even when I wasn’t engaging it. Other weird stuff was happing too. I swear the rear defroster light was blinking too. I drove it around for a little while to charge up the battery. I also put my dad’s little scan tool on it and it said that a bunch of emissions sensors were not communicating or something. After a while the check engine light went off. I think the sensors were just reseting after the car dying. But it doesn’t explain the blinker stuff. Also, after leaving the car parked, randomly different lights would flash. I think they were in tune with the blinker clicking when it was not supposed too. Did I ruin my car? Any help would be appreciated.

PS - the flashing lights were the rear lights and the blinker lights, not interior lights.

The things you describe are caused by letting the battery go dead. You need to put a charger on the battery to bring it back to full charge. The alternator is not enough.

You need to keep it on a battery tender on it to prevent this in the future. I’d get the battery test after charging it to see if it needs to be replaced.