Microsoft will but, being that it has only been a few days take it back to the store or ship it back. Microsoft is pretty good and quick about replacing items but, that turnaround will be quicker from a major online store (like Amazon, GameStop, BestBuy, etc..) Don't treat as it is special and think opening it voids anything. People seem to be tip toeing around returning it. It is no different than any other item you buy.
Every device has issues. Especially true for the initial run of a new device with many moving parts like these consoles. The failure rates aren't much greater then normal. You just hear about it more because people are more focused on the device What little issues that are common will be ironed out at the manufacturing.
The PS4 Pro had fan issues as well when it was released last year. It also had weird power and erratic system issues. I was one with a bad PS4 Pro fan (you could hear from the other side of the house) and returned it back to GameStop. The second device had an issue where it wouldn't eject the disc and power up didn't always work. Returned that one. The third time was the charm as they say in my Pro case.
So far my Xbox X has been working like a charm. It is slightly louder than S but, not drastically so on normal operation (just ever so slight). However, it can be noticeably louder then the S (still quieter than my Pro) mostly when it is running true 4K game. Which is to expected as it really is pushing the APU at that point over the less expensive 1440p or 1080p renders.