The iphone screen home button connects through the screen connectors.
There is also a small connector on the screen near the home button.
Check the small connector, can’t remember if it was to the left or right of home button (left I think) but it clicks onto a connector that is glued to the back of the screen. If this is OK, re- seat all your connections that go to the screen, be careful though, they should not be forced and should click in with a small amount of force when lined up correctly.
Hope this helps.