Step 1: Diagnosis
Turn on the iPhone X, the systems says that unable to activate Face ID on this iPhone. Go to Settings to reset Face ID, it prompts that the Face ID is not available, try setting up Face ID later.
Step 2: Troubleshooting
Shut down the iPhone X, use screwdriver to remove the screws at the bottom of the screen, and then use screen sucker to open the iPhone screen. Disconnect the iPhone X battery, remove the iPhone X display assemble.
We can see that the iPhone X infrared camera flex cable is broken, which could be the reason that caused the iPhone X face ID doesn't work.
Carefully remove the iPhone X Face ID components by tweezers; the infrared camera has obvious signs of breakage.
Apply some high temperature resistance tape to fix the infrared camera flex cable, and then use BGA removal blade to scratch off insulation paint on the flex cable, and then clean it with cotton swabs.
Because the iPhone Face ID components can't be replaced, so we need to solder a jump wire on the broken flex cable.
Apply some solder paste to the broken flex cable, use AIFEN A9 Pro Soldering Station to heat it, apply some tin to the broken flex cable, and then clean it with PCB cleaner.
Apply some solder paste to the broken flex cable again, use soldering iron to solder the two ends of the 0.02mm copper wire to the two pins of the broken flex cable, and then use BGA removal blade to cut the extra wire.
Once done, check the flex cable to make sure there is no virtual welded or short-circuited, and then clean it with PCB cleaner.
Apply some green UV oil to the jump wire to insulate it，put is under a Qianli UV Curing Lamp to solidify the green UV oil, and then apply a high temperature resistance tape on the jump wire area to protect it.
Step 3: Assemble & Test
Now install the iPhone X Face ID components to the iPhone X, turn on the iPhone X to test the iPhone X Face ID function, the iPhone X Face ID can be set successfully, and the iPhone X Face ID is working properly.
So, now you know how to fix Face ID if it’s not working on your iPhone X. Or if you have any further questions, let us know in the comments below, we’ll be happy to answer them.