If under warranty then very simple. Just create the support ticket online - they will email you the shipping label and arrange pick up time - you pack your device securely and stick the label on and hand it over to the courier - once MS receives it then they will inspect - if no issues with the warranty claim then the next email you'll get from them is them tell you your replacement has been shipped out. Whole process probably 2 weeks max? Not sure how COVID would've affected this timeline.