Reset the Frigidaire oven and the self-clean cycle if the door remains locked after the initial self-clean cycle has finished. If this does not work, access the lock and unlock it manually to get the door open, using the owner's manual to get inside the oven.
Go to the circuit box, and turn off the switch that powers the oven. Wait five minutes, turn the circuit switch back on, and set the oven's clock. If the model has a lever, try moving it to open the door. If the door is still locked, set the oven to self-clean again, and run it for 15 minutes. Afterwards, cancel the cycle, and let the oven cool. Try to open the door again. If this doesn't work, check the owner's manual for additional steps. If you still can't open the door, you need to find the lock.
Most self-cleaning ovens use a solenoid-driven, motorized or heat-activated locking system for the doors. The Frigidaire owner's manual should indicate how to get to the locking system. Motorized and heat-sensitive locks are usually located under the cook-top. For a built-in oven, you may need to slide the oven out of the enclosure to take the top panel off to get to the lock. Some models have the lock assembly accessible behind the control console. In a solenoid-driven model, the lock mechanism is accessed through the back of the appliance, although some built-in models have it under the top near the front. Contacting a service professional may be necessary to keep your warranty valid, or if you don't feel comfortable taking your oven apart.