Surgery success! (iPhone 4 home button replacement)
My iPhone 4 home button stopped responding months ago. The only way it would work was to apply the pressure of a thousand dying suns with my thumb. I'd had it. The home button repair was daunting, but your guides gave me the confidence to attempt it.
Disassembly was easy.
I almost tore the home button mount out when I mistook it for part of button's ribbon cable, but thought better of yanking too hard before I figured it out. Carefully examine this attachment in strong light before you attempt to remove the ribbon, and be sure you remember to flip up the microscopic clamp on the front of the mount before pulling. After installing the new home button, I was concerned about not pushing the ribbon in far enough to be confident it was contacted. But the wider part of the lead does not need to be flush against the connector for it to work (confirmed this after reassembly).
Second issue I encountered was that when sliding the flex connectors through the screen bezel to reattach, the longer cable would not reach the connector on the logic board. After removing the screen twice (10 screws! argh!), I discovered part of the ribbon was getting folded under the bezel. Be sure you pull this ribbon connector ALL THE WAY through the case or you will be removing the screen again later. Some of the wider/squarish part near the screen attachment point needs to be fed through as well.
The video guide doesn't specify that you need to remove the ring vibrator (2 screws) to access one of the screen screws, but this will be obvious when you get that far. Just don't try to force the screen apart if you don't have all 10 screws in front of you.