Home Button Not working

Hello guys,

i have a verry strange problem now, its like i damaged my logic board i think but i want to make sure...

few weeks ago i rebuild my iphone black to a gold white phone , all set in place and all work fine except the home button, the home button does nothing anymore,

first i taught i damaged the flex cable or the dock connector , i orderd a few home cable's & dock connectors to make sure that that is the problem.

but it seems not to be working, i try to reassembly my phone back in the OLD housing and it still doe not work so now its damaged all the way...

is there a chip that i might damaged why pulling out the battery or the logic board.

or is the problem something else