Chosen Solution
So I undertook a full rebuild into a new body / housing and a new screen. The Touch ID / home button flex was damaged on removal. Touch ID still worked but no home button. I replaced it with a basic version. This appeared to work OK. I had to take the screen off again to fit another lightening port due to a muffled microphone. Sadly I cracked my new screen. Pleased with how my phone was performing I fitted a new screen. So now the home button doesn’t work??? I refitted the old screen to rule out a fault with the new screen. It wouldn’t work with the original either now. Even the Touch ID with the original button now wouldn’t work. Tried a full reset and checking connectors etc etc. Tried the front camera change. I have ran out of ideas. Could I have physically damaged the logic board.
so to be honest it sounds like either your connector is worn out from removing and reinstalling multiple times, IE bent pin or lifted ribbon pad kinda thing. it could also be a lifted component on the board by the connectors themselves. if you have a jewelers inspection lens look at the filters and resistors on the board and make sure none are broken before you get the new cables. also check the female connectors for any bent or missing pins as well. these things are microscopic so just because you cant see it doesnt mean its not broken on the component level. i had a resister that was so small that i literally thought was there because the solder joint was so close it looked like it was there. used my microscope after about 4 hours of chasing stuff and i found it. i hot air stationed it and installed a new resister and it was good to go after that! good luck!
close up of the connectors.
