I see you are doing this for someone else and you are new to iFixit, so I would say this is beyond your capability at this stage. This is a job for a micro soldering expert.
They may be able fix the home button, so that it works again, but will probably not detect fingerprints any more. Sometimes the IC Turtle chip gets dislodged from the home button flex. There is also a Bluetooth Home button work around that can be installed, it is called the JC home button, google it o find out more.