As mentioned elsewhere, directly underneath the camera there is a tiny patch of conductive metal-mesh tape - not shown in this picture. It seems to connect the midframe to some other part. It might not be essential? I accidentally loosened it, and use two strips of adhesive tape on top of it, slightly overlapping, to bring it back to its place.

What kind of glue did you use? I suspect that a) it could change the contact of the ribbon, therefore hindering conductivity and b) that the glue might change over time, e.g. break down and cause side-effects.