Chosen Solution
If I bought a iPhone 6 can I swap the battery, screen, logic board to test a no power phone like a iPhone 6 Plus or S or S plus. Doesn’t matter if screws don’t line up, just for testing.
You can only use an iPhone 6 logic board for an iPhone 6, same goes for the other ones. They have different plug points, different power for the battery and the display. TD:LR Don’t do any board swapping unless it matches with the very same model and size.
Unfortunately they aren’t transferable, don’t expect Apple to use the same connection style of different generation of iPhones parts.
