Console repaired or exchanged?

I have a question and indeed, tomorrow I get back my commissioned XBox One X from Microsoft. She is currently on her way back. Now my question to those who have any idea or have already sent an XBox before: How can I tell if it is my console that has been fixed and if it is a new, exchanged console?

The serial number you probably did not write down. Basically, it does not matter if you get a new one or not.

I know from my time that Microsoft exchanges rather than repair.