Does replacing the CEM reset the whole electrical system?

What is your question?

Over two weeks ago my XC90 with 2500 miles experienced electrical system failure. Dash went black, no turn signals, RPM and MPH flatlined to zero, no air/heat controls, and no window usage capability. Car was taken to German dealership (I'm an American living in Germany). They had car two weeks and said they replaced the CEM and updated software. So I get in the car and the radio automatically syncs to my phone Bluetooth and starts playing music and then I checked and my station presets are still there. This is a bit fishy to me. If they replaced CEM, wouldn't the radio need to be reset with my preferences? My seat memory also worked to my settings without me having to reset. I am by no means an auto technician, but I would think I would have to reset my preferences on some of these things just like if the electricity in a house went out and I had to reset clocks, microwaves, etc. Any advice/feedback? Thank you!