Assign a device that was serviced or replaced in Apple Business Manager
Service a device
You should un-assign any devices from their mobile device management (MDM) server in Apple Business Manager before they are 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 Authorised Service Provider, the replacement device is usually also available for enrolment. 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.