Assign a device that was serviced or replaced in Apple Business Manager
Service a device
You should unassign any devices from their mobile device management (MDM) server in Apple Business Manager before they’re subject to AppleCare service.
When the device is returned, you can reassign it to the same MDM server.
Replace a device
If you replace an iPhone, iPad, Mac, or Apple Vision Pro currently enrolled in Apple Business Manager through an Apple Authorized Service Provider, the replacement device is usually also available for enrollment. You can manually assign the device to a server using your order number. To find replacement devices, search for order numbers that begin with the letter R.