Gently bend the Jimmy outwards to pry the crack open a little larger and lift the lower housing up a small amount.
There are several plastic clips on the lower housing that fit into a channel in the aluminum top housing. Your goal is to use the Jimmy to push these clips inward enough to free them from the channel, while gently pulling up on the lower housing.
If your mini does not have Airport installed, then skip this step.
Grasp the Airport antenna board and lift it off of the two plastic posts holding it in place. You may need to push back the black plastic tab jutting through the lower left corner of the board.
If your mini has neither an Airport card nor a Bluetooth board, you can simply lift the optical drive up and away. Otherwise, you need to disconnect the Airport and/or Bluetooth antenna cables first.
With your free hand, pull the Bluetooth cable up from Bluetooth board and unplug the Airport antenna cable from the right of the Airport card. Caution: both of these connections are very small. When re-assembling unit after repair, you may want to remove the two screws holding the airport card to the assembly and lift the card up and out to re-attach the cables.