How to find out what Apple returned to the factory for maintenance?

How to check the maintenance progress after the iPhone is sent to Apple for after-sales maintenance? 1. Enter Apple official website first. 2. After entering Apple official website, choose technical support here. 3. Then drop down the webpage and select it in the lower left corner to view the maintenance status. Enter the maintenance ID and serial number here for query. Generally, it takes 6 or 7 days to inquire after delivery to the after-sales outlets.