It can take several months for smells inside the refrigerator to dissipate. However, the following steps will assist in riding your unit more quickly of unpleasant odors:
For hard to remove smells spilled in the refrigerator, like fish or shimp juice, take a breath mint and wet it. Place the mint on a paper plate or bowl inside the refrigerator section. Leave the mint in the refrigerator (dampening it periodically) to allow the mint to circulate throughout the unit. Leave the mint in for only 2 or 3 days. Depending on how bad the smell is, it could take a couple of days, weeks or months before the smell is completely gone. Keep repeating this process until the smell is gone or if it starts coming back.
For severely embedded smells, turn off the refrigerator and remove everything from inside. Wash the refrigerator walls, bins, drawers and shelves in a 50/50 vinegar and water sollution. Then rinse them in a 50/50 solution of lemon juice and water. This will remove most of the smell from the plastic, but not all.
Put everything back into the refrigerator except the food. Go to the pet store and purchase activated charcoal. Place charcoal in the bottom of paper bowls (one or two bowls for the freezer and one or two for the refrigerator sections).
Open two boxes of baking soda and place one in the freezer and one in the refrigerator section. Roll pages of newspaper into loose paper balls and place several on a paper plate. Make enough newspaper/paper plates to place one on each shelf in the freezer and refrigerator. Place one drop of cooking vanilla on one of the paper balls in the refrigerator section.
Turn the refrigerator on and close the doors. Depending on how bad it smells, wait a could of days or a week and repeat the above steps. You will gradually notice the smell disappear and be able to use the refrigerator again.