If it's the motor that's noisy or possibly not working at all, either of these may be the "culprit:"
As motor bearings wear out, they can become quite loud when the motor runs. They wear out quickly if they frequently get wet, because the water washes away the motor bearing grease. Bearings can get wet if the spin seal is defective. Then there will also be water leaking onto the floor beneath the dishwasher. Replace the seal if it leaks (read about the main tub seal in the "It leaks" section, later).
If, from beneath the dishwasher, you can see a round, plastic disc that's mounted to the top of the motor (a "slinger"), it may have broken free of the motor shaft. If so, it could be rattling around the shaft while the motor is running. If that's the problem, you need to replace the motor.
Now with both of those being said, the motor is not a typical DIY job in my opinion. For the safety and accuracy of yourself and your appliance, I would contact Frigidaire and then a service professional to complete the installation for you. While you might be able to find DIY videos on the internet, they are not endorsed by Frigidaire and will most likely void your warranty if you try to repair the unit yourself.