Unable to reset passcode in iPhone after restoring it

My young niece was playing on my iphone and has erased to factory settings and I'm stuck on the hello screen. It's asking for a passcode which I know don't know. Its wrong after many attempts so it locked for 8 hours. After trying to restore using the method below and a Mac it's locked again for 8 hours despite no passcode? How do I fix this without the restore? Is there any way to get into phone without knowing this code? I have the original box.

If you’ve forgotten your iPhone passcode or your iPhone is disabled – Apple Support (UK)

[Re-Titled by Moderator]