Frigidaire FRSS2623AS Use & Care Manual page 27

To reassemble the freezer shelf, slide the
glass and rear trim along the shelf rails
while pressing the shelf downward until
it is fully locked into place in the rear
(Figure 3).
Figure 3
CARE AND CLEANING
Finally, rotate the front trim upward on the
front edge of the glass shelf (Figure 4).
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Figure 4