I can't restore Apple TV 4k using an iPhone

… using an Iphone.

What does iPhone have to do with it? That shouldn’t be involved in restoring.

To reset when you still have access to the menus:

Reset or restore your Apple TV to its factory settings - Apple Support

To restore when you can’t access the menus anymore (i.e. when in ‘recovery mode’):

Restore your Apple TV - Apple Support

↳ If you have an Apple TV 4K, then contact Apple Support.

Like this? If your TV shows an iPhone next to an Apple TV - Apple Support

That procedure may not apply if you do not get the on-screen symbol as depicted.

That page ends with: “If these steps don't work for you, contact Apple Support.”

No