iPhone 6S on 11.3. I just replaced the rear camera assembly and the front camera+light sensor+earphone assembly with third-party parts (on a moving train, I mig

iPhone 6S on 11.3. I just replaced the rear camera assembly and the front camera+light sensor+earphone assembly with third-party parts (on a moving train, I might brag). Everything works except the auto-brightness setting disappeared. I did Erase Settings and it's still gone. I'm wondering if: - I didn't place the light sensor correctly - I touched it/ruined it - the part is defective - Erase All Content & Settings options is absolutely necessary