Stuck in Guided Mode

My Dad's iPhone is partly stuck in Guided Mode (it lets me navigate around the app, when it shouldn't) and it says password to exit Guided Mode is wrong...but it's not. So, my Dad can't access his phone.

His phone is used as a Freestyle Libre diabetes sensor reader, which sends a message to his family care team to let us know when he’s high/low, so we can intervene in a hypoglycaemic event.

The phone doesn’t have a passcode, so when I reset the phone, it goes straight back into guided mode.

When I use iTunes to change settings that way, it sends a two-factor authentication message to the same iPhone that’s stuck in Guided Mode. So I can’t access that either.

iTunes say they will be in touch, but it may take some days for them to…

We’re in a real predicament now, because my Dad isn’t well enough (stroke survivor), to check his own blood sugar levels and the app says it’s lost signal with the sensor, so I need to scan the sensor, but it won’t let me (the only feature of the app that won’t work).

Anyone any ideas?? It will save us from having to travel to my Dad’s at 3am to pinprick his finger to measure his bloods.

Thank you