Erase phone with broken home for forgotten screentime password

Hi,

First of all, a happy new year to all!

I've forgotten my son's screentime passcode which I had set on his phone. I set is from his phone, not as a parent through family.

Now, I've been trying to wipe his phone to put on a new passcode through family. But that proves harder than expected, the main culprit seems to be the broken Home button, as the procedure for a 6S running iOS13 is to restart your phone while holding the home button pressed in (https://support.apple.com/en-gb/HT204306).

Next, I've tried erasing it through iCloud (https://support.apple.com/en-gb/guide/icloud/mmfc0ef36f/icloud), which worked fine, but when I set up his phone again logging in with icloud credentials, the screentime passcode hasn't been reset.

Any help is welcome...

I don't know what is happening....

Is it possible I have set the passcode on his phone as a parent? Can I wipe this one then?

From my mac I can't see our son's name under Screen Time in System Preferences. Our computer is a little slow now , so it hangs when I try accessing Family Sharing in System Preferences. Will update the post when I have accessed it.

Thanks an a happy 2020!