Getting an error while installing iOS 15
software error while update iOS 15 and face lock is not working
iPhone 11, iOS 14
Update phone
Click on this link
Update your iPhone, iPad, or iPod touch - Apple Support
Phone will not update
If your iPhone, iPad or iPod touch won’t update - Apple Support
User Tip updating iOS
Updating iOS: common issues and solutions - Apple Community
Check out the article If an alert says Face ID has been disabled on your iPhone or iPad Pro.
See if anything in the support documents helps bring resolution else contact Apple Support.
If you had the screen replaced other than by Apple it will never work again