A step by step guide to open an iPhone X for repairing (LCD replacement, battery replacement, motherboard replacement/ repairing etc.) This is guide is for professional mobile phone technicians and needs proper tools. Please do not try this at home else you will end up damaging your phone) iPhone 11 opening guide for repairing For complete guide please visit ifixit website
If iPhone X face ID function is no working and software updates do not solve the problem then solution is to replace FaceID Sensor IC U4400 STB600B0. This faceid IC should be replaced by expert technicians and require hot air gun or infra red soldering machine. Please do not try this at home else you might damage your phone permanently. IC required: U4400 STB600B0