I'm wondering if it would be a good idea to bend/crease the new ribbon cable to match the bends and creases from the old ribbon cable, (being careful not to damage or break new cable), to aid reassembly of the phone as it was like trying to get a jack in the box back in the box as it were... just a thought.
READ - as Dave & Jason have both pointed out, the small black clip needs removing first.
This clip has two legs with inward facing prongs that extend down either side of the housing.
The leg on the left side appears to locate into a hole at the base of the housing, the right side slides back and forth in a horizontal slot.
I found the easiest way to remove is to first push the ribbon cable as flat as possible, to allow for the clip to slide over it, and with a small flat blade screwdriver come in vertically, don't try to get under the clip, in the top right corner between the clip and the housing.
Twist you screwdriver clockwise and you'll see the right side of the clip slide downwards toward the speaker end of your phone. Keep pushing this side until the prong clears the housing, then use tweezers to unhook the left prong.