Chosen Solution
so my iPhone 7 had a cracked screen so I bought an ICloud locked 7 with a good screen to fix mine with, both phones home buttons functioned perfectly fine before the repair, I took the home button original to my iPhone and put it into the replacement screen, and the home function nor the Touch ID is working, I have completely taken apart the home button assembly and put it back together, I have even tried both home buttons and they don’t work, I have also carefully inspected the cables but none have any visible damage, I don’t know what else to do so I’m asking this community
Let’s call your original phone “Phone A” and the for-parts model “Phone B”. You say you moved Home Button A onto Display B, and Home Button A didn’t work. If you put Home Button A back on to Display A, does it work on Phone A? If so, then either Display B is bad or Home Button A wasn’t seated properly on Display B. If not, then Home Button A was damaged during your repair attempt. The Touch ID circuitry is RIDICULOUSLY delicate and very easily damaged.
Have you afther you switch the screen and home-button connected the iphone with itunes and restore it? Sometimes this will help.
