This has been common knowledge on this forum for years and years and has been restated recently.
It must be programmed for a certain VIN with a code that is seemingly only known to Chrysler and they share this info with just one subcontractor who does the work on the SKREEM modules. Mercedes has no input in this matter and is helpless to do anything about it even if they wished to, which they don’t.

The attitude by Mercedes on the Crossfire is very odd, and has surely cost them customers who currently have or have had a Crossfire. Surely a policy that deters customers is not one that any corporation should have. Likewise Chrysler’s attitude is very similar, no one wants to do any service unless it is easy, like oil changes and brake jobs.

The whole affair seems like an unresolved battle in a divorce court over support for a child that neither parent wants the responsibility for, the only loser being the child.

I think that a SKREEM module from an identical or maybe just similar car which has had the VIN number and the key info from the old unit added should do the trick. Would there be a need for another level of security like a secret number matched to the the ECU? I doubt it but who really knows.
We have a top notch technical whiz who works for Chrysler, and he has not had any input on this lately.