Use a heat gun to soften the adhesive underneath the camera/microphone cover.

Pry the camera/microphone cover off the case with a metal spudger and remove it.

Use a hot glue gun to apply a bead of glue across the cover.

Move the nozzle in the glue for 20 seconds to heat the lens adhesive holding the lens in place.

Press a spudger into the hot glue and hold it in place until the glue cools and hardens.

Pull on the spudger with firm steady force, while using a fingernail to pry on the cover edge.