Can’t sign in on xbox

My son is having trouble signing into his Xbox. He said the Xbox app on his phone kept throwing him out so he uninstalled and reinstalled it. He’s signed in on his app but his console is not connected.

When he tries to sign in on the console it prompts to scan a QR, enter the code and get a verification code. The verification codes don’t seem to be coming through to his email so we’re using the face recognition which seems to work. The screen on his phone tells him he’s all signed in but the Xbox screen is stuck on the QR code page.

We’ve tried turning off, pulling the power plug etc but still couldn’t get logged in.

We’ve removed his account and seemed to get further adding his account back on but it gets stuck on a password screen which just goes round in a loop. We’ve tried his password and adding a new one but still goes back to add a password.

He’s also had emails confirming sign in detected on a new device - so it seems to think he’s signed in successfully but Xbox is not showing that.

We’ve signed into his Microsoft account via account.microsoft.com and his Xbox is linked there.

Not sure whether to remove the device from the Microsoft account and / or try a factory reset.

Anyone else have this issue and how did you solve it?

:)