Chosen Solution
I have two iPhone 7 plus’s one Was working completely fine Until I decided to test out the screen on the broken one that Is waiting for parts. So the broken one needs a new screen and a battery I replaced the battery and figured well lets test it out with my phone that’s currently working so I took of the screen and attached it to the other and everything turned on and worked except the home button the touch it and the ID witch I was expecting but when I put it back on the original phone only the touch ID works and not the home touch its self I have to use the assist and also now the volume will not go up or down with the buttons it registers me trying to turn it up and down but doesn’t do anything. I tried a hard reset a factory reset and I am just all out of ideas !
As for the volume buttons. Check that the cable is plugged in and not ripped cause it runs under the battery so it is possible that it was cut. They are very fragile and thing cables.
If the click function doesn’t work but the Touch ID does, then that is caused by a damaged IC (Turtle IC / U10) on the home button flex. This typically happens when the flex is transferred from one screen to another. The IC is sitting on some tiny solder balls and when the flex is pried off the screen, those solder balls can crack or break. This can be repaired but requires a micro-soldering repair.
Try to change the home button from other display and see if she’s working and try to make Rest of ur phone
