Clearly, it is preferable to have one’s mezuzot checked by a reliable sofer who is trained to pick up subtleties that the layman’s eye might miss.
However, since your mezuzot were already checked by a professional sofer, the purpose of re-checking them now is mainly just to see that the letters have not cracked or otherwise been damaged by moisture or sun exposure. According to some opinions, this kind of checking can be done by a competent layman, when necessary.
If you do not find any problems, you should immediately return the mezuzot to their posts. In this case, no new berachah is recited. Ideally, one should put them back without delay, as there are some authorities that require a new berachah after just a few hours, especially if one has engaged in other activities in the meantime.
If you will be placing a mezuzah on a doorway where it had not been affixed beforehand, you may make a blessing even before the next day. However, you should make sure not to “demote” the mezuzah by moving it from a doorway whose obligation is clear to one whose obligation is doubtful.
 Chasam Sofer Y.D. 283, cited in Pitchei Teshuvah Y.D. 291:3. Others contend that one who has not studied the laws of Safrut might not notice finer invalidations which may occur even to Kosher scrolls through decay. [2nd Ed.]
 Shach Y.D. 186:25; Chidushei R. Akiva Eiger, op. cit.
 Sha’arei HaMezuzah 17:22; Agur B’ohalecha 7:23.
 Aruch HaShulchan Y.D. 289:4; Teshuvos V’Hanhagos 2:551; Kovetz Mi-Beit Levi, Tishrei 5751; Sha’arei HaMezuzah 20:15; Leket Shut Mezuzzos, citing R. Eliashiv and R. Wosner.
 Rema Y.D. 289:1.
 Agur B’ohalecha 7:24:69; Sha’arei HaMezuzah 17:22:46.