Restart the iPhone; Attempt to complete Face ID enrollment continuously for at least a full minute in a well lit environment. Should you continue to receive this exact error, 'Face ID has been disabled' or 'Face ID is not available' then bring in the iPhone for an inspection: iPhone Repair & Service
Problem: The iPhone X shows an alert that says it is ‘unable to activate Face ID on this iPhone’. Troubleshooting: 1. Face ID relevant circuit has probably malfunctioned. We need to check components on Face ID relevant circuit. 2. We can see that the infrared camera module flex cable is broken. Solution:
Simple screen replacements on the 11 Pro Max do not "permanently brick" face ID. If there's an issue with face ID, it's either coincidental damage, damage during repair, an incomplete repair, or the forehead flex was swapped out. Also, Apple doesn't have machines to reprogram replacement parts.
OIYB.