Like other large appliances, refrigerators are expensive to buy so you want yours to last a good long time. The outside of the cabinet is made from a fairly durable metal. The inside liner, however, if usually made of a hardened plastic. It's made to last for years to come. If a hard object comes forcefully against the liner, it can crack or break.
Remove all food and beverages from inside the refrigerator. Remove any shelving that may be in your way. Unplug the refrigerator and open the door. Allow the plastic liner to come to room temperature.
Hang the trouble light up so you can see inside the refrigerator, but so it's out of your way.
Use the power drill to very slowly make a small hole at one end of the crack. Be careful to drill just through the liner and not any further. Then, drill a small hole at the other end of the crack. The holes will prevent the crack from spreading across the plastic.
Check to make sure the affected area on the liner is clean and dry. Wipe away plastic shavings. Then, wipe over the area with rubbing alcohol on a cotton ball to remove grease and oil.
Use a food grade silicone sealant to repair the crack and seal the holes. Read and follow the manufacturer's directions in order to achieve the best results. Repair a small hole in a plastic refrigerator liner by simply sealing it closed in the same manner. You don't need to drill any holes.
Fix cracks and holes inside a refrigerator by ordering a plastic liner repair kit. You'll need to order according to the brand and model of the refrigerator you have. The Repair Clinic website (see Resources), for example, sells these kits. You'll need the model number of the refrigerator to get the correct kit.
You can purchase a food grade silicone sealant to repair a plastic refrigerator liner at restaurant supply houses.
For your own safety and protection, only use "food grade" sealants for this task. Ordinary sealants can contain harmful chemicals.