To remove and re-attach the blades from the SZ360 Powered Scissors:

Separate the scissor blades and set the top lock slider switch to the "OFF" (0) position prior to removing the heads.
To exchange the cutting heads, grasp the scissors with one hand at the base of the unit with one hand, and press in on the sides of the cutting head, pulling straight out and away from the unit. I've found it's easiest to squeeze the gray portion of the cutting head as close to the base of the unit as possible for easiest maneuvering.
To attach a cutting head, line it up with the body of the scissors and push it on until it snaps into place. If the cutting head does not line up easily, carefully separate the blades from each other first, then re-attach.