Chosen Solution
The Touch IC has been replaced*. Touch is working fine now. The Home Button stopped working, Touch ID is working. When you press the Home Button, nothing happens but the phone delays a bit while unlocking it afterwards with the power button. When holding the power button, the phone performs a hard reset as if power and home are pressed together. Different Buttons, Displays, Cables….have been tested. Its safe to say that its Board related. My expert friend and i are clueless at this moment. Any Ideas?
My guess is you might’ve accidentally applied too much heat to the board during reflow. I do also agree with Ben that reflowing is a very temporary fix and strongly recommend replacing or letting someone replace it for a longer lasting result. The overfill on the other side of the board that covers a series of filters capacitors and resistors expands when enough heat is applied. If the components related to the home button lift off with the overfill you’ll most likely experience problems using the home button itself. I would do a visual inspection of the mesa connector (home button/touch id connector) and make sure it looks good, then apply very low heat and pick off the overfill on both sides of the connector. A schematic should show which components are related to the connector itself. Make sure all components are securely attached to the board and not coming off. Re-solder any loose components and test the home button. I also would not re-apply high heat on that side of the board with overfill as you could do more damage.
