When set up mode do you refer to set up assistance?
Take a look into this article https://support.apple.com/en-us/HT201274
If your device has a restriction code (screen time) it also tells you what to do
You're going to have to reset the device back to factory and go through the setup process again. Make sure you know all your account info before doing so as you will be asked for it. It may also help to have another Apple device handy logged in with the same account credentials in case you have 2FA enabled on your Apple ID.