The different cords are because there were 2 style iPad 2 wifi. I snapped a picture of 2 empty iPad 2 cases, both A1395. One is what I call an iPad 2.5 since they did change the innards.
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You can interchange parts on them without a problem. Its a pain taking the top apart though, which is what connects your buttons and camera to the board.
When you say you know all the parts work, how did you test that? You say you have another iPad 2, what happens if you connect one of these boards to the 3rd one?