Here's how to pair your new case with your old AirPods
Pair your new case with your old AirPods in just five simple steps:
Forget your old AirPods
Go to Settings → Bluetooth
Press the i in the circle behind your old AirPods
Press 'Forget this device'
To upload
Place the old AirPod(s) in the new case and charge it for at least an hour.
Reset
With the case lid open, press and hold the button on the back for about 20 seconds. Release it when the flashing light changes from white to orange.
To wait
Wait until the light flashes white or green again, close the cover and open it again after about 30 seconds.
To link
A pop-up will appear on your phone to pair your new AirPods. If not, go to the Bluetooth settings and pair them manually from there.