Advanced Bionics Naida CI M90 Manuel D'utilisation page 58

To close the M Listening Check when not in use, remove earbuds, and
then grasp the grip indents on the side of the M Listening Check with
one hand while grasping the sound processor and battery interfaces
with the other hand. Carefully pull your hands apart until the two pieces
disconnect.
Turn one piece 90 degrees, align the AB logo piece to slide into the
other piece. Push together until it snaps into place.
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