Be super careful handling this ribbon particularly. I did a battery install and, when I was done, I had a phone with a new battery and no Face ID. That’s a $300 Apple repair, and no 3rd party shop will touch it. I believe the ribbon lays vertically (i.e., perpendicular to the “floor” of the phone, against the side edge of the battery. During the re-install, I must have forced the ribbon into position after seating the connector, causing fatal flexing of the ribbon. (Don’t know this for sure, but I see another comment saying that this cable is part of Face ID.) Anyway, bottom line: BE CAREFUL REMOVING AND REINSTALLING THIS RIBBON!