1. A customer's iPhone 7 touch ID would not recognize their fingerprint due to sweaty or wet fingers. 2. Checking the settings revealed the touch ID was grayed out, indicating a problem. Disassembling the phone showed the home button flex cable was broken. 3. The technician used professional tools to remove the cable's coating, apply solder paste flux, solder the connections, and fix the weld joint with UV curable solder mask. 4. After reassembly, the touch ID was working normally again.