Okay, thank god you are on iOS 12.3.1. That way, it makes life easier. So, backup your iPhone to iTunes, along with encrypting your backup. Then, setup your password and back it up. Here are proper steps. Or, the risk free way is below.
- Connect your iPhone to an iMac or a MacBook.
- iTunes should launch. If not, launch it yourself.
- Click the icon somewhere in the top left for iPhone.
- Back up your iPhone to iTunes with an encrypted backup (Click Encrypt Backup after clicking iTunes backup, and set your password. REMEMBER IT, YOU NEED IT. I would recommend setting it as either your Apple ID password, your device password, or something like 0000).
- ‘Finally back it up fully. Try making 2 backups just to be sure.
- Archive your Backup by clicking up at the very top of the screen Preferences>Devices> Right Click on Backup> Archive. It should now have the time and date.
- Time to wipe the device.
- Restore the device with that Archived Backup. You will need to use the password you set for the backup earlier.
- Pair your AirPods again.
- If it doesn’t work, then I’m not sure how to help you.
I understand this is a large stretch, but thank god you are on iOS 12. You can save much more data. Remember, this comes with its own risks, and I am not liable for data lossage. If you do not want to take the risk, contact Apple Support through their app “Apple Support” or through an Apple Store.
Good luck mate!
Here are my sources: https://www.macrumors.com/how-to/create-an-archived-itunes-backup/
https://www.macrumors.com/how-to/encrypt-ios-device-itunes-backups/
https://support.apple.com/en-us/HT205220