You aren't getting flamed, you are getting good advice.
In post 1, you specifically asked "what dealer" to take the car to - the answer is NO dealer.
You then indicated a shop or shops have told you that they "don't have the device to read the codes" - this is asinine BS, any $70 code reader will read the DTCs in these cars. What NONE of us have, is the STAR computer to read the cars - and yet, most of us here can service our own cars just fine. What I am saying, is that the shops you are talked to simply don't know what they are doing, and hide behind the 'it's a rare car and we have no equipment to service it with" thing.
The spoiler problem WILL NOT be solved by ANY computer, code reader or similar. Take our word for it, it is battery-related OR it is a bad wheel speed sensor. The very vast majority of the time, it is one of those two items (well, it can also be the traction control relay but usually you get some significant other symptoms - like no speedometer indication) . And I will say it again, there is no reliable way to test the battery in this scenario, replacing the battery is your only diagnostic tool - and it's way cheaper than paying a 'tech' $90 an hour to fiddle around. If the battery is new, another cheap trick is to do one of these two easy mods that any shade tree mechanic or local shop can do - you don't need a dealer or "Mercedes specialist":
https://www.crossfireforum.org/forum...le-engine.html
Owning a Crossfire is very enjoyable if you are at least a bit of a mechanical or "techy" car guy or girl. Owning a Crossfire when you are one who only takes cars to dealers for service is NOT an enjoyable experience, in most cases. Tech support for our car is GONE; Chrysler dealers are not familiar with the SLK320 at all - so service at any dealer is usually an expensive and horrible experience. We cannot fix that, no one can.
As to the TPMS - I'm happy my SE does not have that feature. The TPMS in these cars is a unicorn, and it has caused TERRIBLE frustration and expense for MANY owners. Clint, one of our members, is a retired engineer who worked on the safety systems in cars including the Crossfire. He has written a great tutorial for owners to use in getting service on the TPMS. I'ts here on this forum somewhere, if I can turn it up I will link to it.
But again, I am thankful my car does not even have TPMS.