Step 1: Confrim the reason
1. Jailbreak the iPhone. Connect the phone to the computer with iPhone Charging Cable. Open the software and click "Start". Enters the recovery mode and then manually enters the DFU mode.
2. Connect the phone to the computer though the J-BOX Jailbreak tool. Click "Face", reading data.
We can find the data of the distance sensor and ambient light sensor don’t match the data on the iPhone X motherboard. So we can confirmed that the earpiece flex cable repalcement results in the Face ID not working.
Step 2: Install the new earpiece flex cable
1. Disconnect the flex cables and remove the iPhone X Screen Display assembly.
2. Detach the earpiece flex cable and install the new iPhone X earpiece flex cable.
Step 3: Repair the Face ID
1. Open the JCID Maintenance Assistant and click "Detect" to unlock automatically.
2. Then we use JC V1S to write the data. Connect V1S and phone to the computer, and attach the earpiece flex cable to V1S.
3. Open the JCID Repair Assistant again. Click "Connect" and start testing. Click “Activate FPC”. Bind the flex cable to the phone.
Step 4: Test
Connect the display assembly and assemble the phone. Turn on the phone to test. True Tone has been restored and Face ID can be set up and is working normally.