My father passed away and I took possession of his 2001 CLK430 Convertible.


I am new to MB and I plan on not keeping in my possession for much longer (it's been hard to transport my disabled mother and her walker in this car) and I'd like to sell it for Summer. Before I can get it ready to sell, I need this problem (that seems to be a common problem but haven't found a direct solution) resolved. I've been digging through forum after forum regarding this issue but still not finding a direct answer of the cause and the solution to fix it. I've found a lot of troubleshooting which some I have done.
1. All four windows not rolling down
2. Window lock light illuminated
3. Convertible button illuminated
4. Left and right mirror adjustment won't work
5. Truck release button on central console not working
6. Lumbar adjuster not working
7. Lamp Defect Malfunction
8. Gas gauge flashes every once in a while
-The last time I had everything working (minus the lamp defect) was on January 19th and I attempted a window resynchronization. We had issues starting it, because my father let the car sit too long. The first attempt to start the car was on January 10th via a battery charger. They let it run for 30 minutes but didn't drive the car very far, just around the block. The car wasn't attempted to start again until I arrived on the 13th but it wouldn't start. I was told they would get it charged again for me to try and take home. On the 16th, I came to pick up the car and found out that the battery was not charged with a charger but via jump started car to car (which I later found out is really bad for Mercedes). ABS, ESP, BAS, and Lamp Defect malfunctions were on the screen. I drove it over an hour away back home and had no problems with iusses 1-6, 8. I drove it on the 17th back to my father's home. On the way back my home, some deer ran out in front of me and I slammed on the breaks. After slamming on the breaks, the ABS, ESP, and BAS malfunctions were no longer coming up but then problems 1-6 started. As far as the Lamp Defect goes, my low beams are affected. They will turn on but are very dim even after replacing the bulbs, I'm still having this issue.
Low beams only:


​​​​With high beams on:



When I replaced the bulbs, my father had these ones (they're also the same type as the high beams):


For 8. so far three times it has happened since driving it on January 16th the gas gauge flash (even though I wasn't my anywhere near empty).

(But flashing)
As you can also tell, the weather temperature gauge also isn't illuminated all the way.

The motor blower hasn't been working since driving it on January 16th (unsure if my father had issues with it prior). It was getting some air/heat blowing through the vents but was not blowing out super hard. Today however when I went to start it, also making sure I wasn't cranking it, (I turned it over, let the key go and let it start on its own) a few seconds later, air is blowing through the vents on full blast. I turned the car off and tried it again and was working perfectly fine, however still issues with 1-6.
*Update* I went back to my car after letting it run for 10 minutes and it's not blowing as hard anymore even on full blast

The last time I had 1-6 working (January 19th) I tried doing the window resynchronization hoping that would work but it's been locked since then.
Is it safe to say this is just a battery issue and would just be best to replace the battery? I've read here that even with battery testing, it won't tell if there are dead cells. Or would this be a SAM issue? Saw someone took the SAM out, cleaned it with electrical cleaner, let it air dry and reinstalled it and everything was working. I'm also reading that it's quite possible I'm even over cracking the car when I put the key in. I meant to stop at Advanced to pick up some fuses and a new fuse tester yesterday but lost track of time with other errands. Weather permitting, I will stop there today to pick that up. I tried testing fuse #7 and it didn't read but unsure if a family friend gave me a broken device (due to his personal neglect for his things) because fuse I tested a fuse that I know would be working (interior lights) and it wasn't reading. Any help would be appreciated.