Не удается выйти из iCloud, iPhone недоступен

The "iPhone unavailable" message is shown for security reasons.

You will have to reset your iPhone, to be able to use it again:

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If you forget your passcode, try Passcode Reset first. If you can't use Passcode Reset, you can then reset your iPhone or iPad without a computer to regain access to your Apple device. Finally, if you can't use Passcode Reset and can't reset your iPhone or iPad on your device, you can reset your iPhone or iPad with a computer.

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1. From your device's Lock Screen, try to enter your passcode until the "[Device] Unavailable" screen appears. 
2. When you're able to, tap Forgot Passcode? The Forgot Passcode? button only appears if you have an active cellular or Wi-Fi connection and have Find My turned on.

3 . On the Security Lockout screen, tap Start [Device] Reset to confirm. 

4 . Enter your Apple Account password to sign out of your Apple Account on your device.

5 . Tap Erase [Device] to permanently delete all of your data and settings. If you use an eSIM with iOS 17 or later, you can also choose to keep your eSIM and erase your data, or to delete your eSIM and erase your data.

6. When your device restarts, follow the onscreen instructions to set up your device again, restore your data and setting from a backup if you have one, and set a new passcode.

If you use iOS 17 or later, the Forgot Passcode? option appears when you are locked out, connected to a cellular or Wi-Fi network, signed into your Apple Account, and have Find My turned on.

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copied from:If you forgot your iPhone, iPad, or Apple Vision Pro passcode, reset your device without a computer - Apple Support

Сброс устройства без компьютера, если вы забыли код-пароль от iPhone, iPad или Apple Vision Pro