It's been a few months since I have flown the Air and honestly can't remeber in what order you turn on the Air, Controller and iPhone.

Hello there, thanks for reaching DJI Forum. First, you need turn-on and re-link your remote controller to your aircraft. After that, kindly connect your iPhone to your remote controller. Please kindly make sure to use a compatible device for reliability purposes. Also, please kindly update the firmware of your drone for compatibility. For reference, kindly watch the video tutorial below. Should you have further question, please let us know. Thank you and have a safe flight.