Even though it is wrapped up and covered, a mezuzah is meant to be rolled in a way that it is readable. Thus, care should be taken that it is affixed right-side up. Also, one should make sure that the Divine name ש-ד-י should be facing outwards, even if the cover is not transparent.
However, a berachah is not recited when the problem you described is corrected, as some authorities assert that a mezuzah placed upside-down still fulfills its mitzvah.
 Mezuzot Beitecha, Sha’ar Hatziun 288:40. Sha’arei HaMezuzah (15:11) writes that this also insures that the mezuzah is placed in a way that the text is “readable.”
 Mezuzot Beitecha 289, n. 62.