I don't know if this helps but you will notice on the transparent plastic camera protector there are two notches specifically spaced on the deeper side of it. This allow it to slot (albeit unsecuredly) onto the camera itself.

The other part that threw me was the noise cancellation tube thing for the mic (or the mic itself) fits into a rubber hole quite uncooperatively.

be extremely careful to check that there isnt any metallic conductive glue sticking, some may remain attached to the motherboard-connecter position in its space on top of the logicboard