After updating my iPhone to iOS 13.5.1, I can't login to my Apple ID - "Verification Failed '' error
I would set aside the phone that’s not working and get control of your AppleID using a web browser on any convenient and secure computer.

https://appleid.apple.com/account/manage

By design it is difficult to bypass activation lock unless you are the original purchaser of the phone and can provide proof of purchase to Apple Support.

https://support.apple.com/en-us/HT201365