Did anything change when the front door lock actuators were replaced?
Were they replaced with new or known good actuators?
Do the old actuators work out of the car when you use battery voltage to lock/unlock? You can probably us a 9v battery to test them.
Does the hatch actuator work?

Power door lock actuators are controlled directly by the body control module. If you hear a click from any of the doors, the BCM is trying to lock or unlock the doors, so the logic is good. All of the motors run off the same actuator circuit in the BCM.

My fault theory is that there is corrosion in a connector which is limiting current to the actuator motors, given that replacing the front actuators did not solve the issue.
Secondary theory is a circuit driver failure in the BCM is limiting current to the lock actuator motors.

I would try first:
Make sure the voltage at the door lock fuse output voltage is about the same as the battery voltage when you are trying to lock/unlock the doors. If you get a fuse jumper, you can also measure the current. I don't see a current specification for it, but based on the 25 amp fuse rating, it should be several amps. If your old actuators are working, you could test one to see how much current it draws.

After that, I think it comes down to getting the wiring diagram and a voltmeter and tracing down if you have sufficient voltage and current at each of the motors when attempting to lock/unlock. IN1, a harness connector at the right kick panel looks like an easy place to start rather than taking a door panel off. The wiring diagram manual is available at Toyota TIS for $20 for 48 hours, or buy the book at Faxon or EBay.

This may help:

 

Did anything change when the front door lock actuators were replaced?
Were they replaced with new or known good actuators?
Do the old actuators work out of the car when you use battery voltage to lock/unlock? You can probably us a 9v battery to test them.
Does the hatch actuator work?

Power door lock actuators are controlled directly by the body control module. If you hear a click from any of the doors, the BCM is trying to lock or unlock the doors, so the logic is good. All of the motors run off the same actuator circuit in the BCM.

My fault theory is that there is corrosion in a connector which is limiting current to the actuator motors, given that replacing the front actuators did not solve the issue.
Secondary theory is a circuit driver failure in the BCM is limiting current to the lock actuator motors.

I would try first:
Make sure the voltage at the door lock fuse output voltage is about the same as the battery voltage when you are trying to lock/unlock the doors. If you get a fuse jumper, you can also measure the current. I don't see a current specification for it, but based on the 25 amp fuse rating, it should be several amps. If your old actuators are working, you could test one to see how much current it draws.

After that, I think it comes down to getting the wiring diagram and a voltmeter and tracing down if you have sufficient voltage and current at each of the motors when attempting to lock/unlock. IN1, a harness connector at the right kick panel looks like an easy place to start rather than taking a door panel off. The wiring diagram manual is available at Toyota TIS for $20 for 48 hours, or buy the book at Faxon or EBay.

Thank you for your reply and for all of the information.

As far as anything changing when I replaced the door actuators, originally, the front driver side door lock was the only one that was not locking and unlocking, so I replaced the actuator on that one. As soon as I replaced it, the passenger side door lock started acting funny and stopped locking and unlocking. It should be noted that even after replacing the driver side front door actuator, the door lock still did not work. After all of this happened, I went ahead and replaced the front passenger side door lock actuator and that lock still did not work. Both of the door lock actuators that I purchased were new and after they did not solve the problem, I even purchased two more new actuators and installed them which still did not fix the problem.

A local mechanic told me that it could possibly be the driver side door master switch that's the problem. I'm not sure if I'm calling it the correct name, so what I'm talking about is the whole unit in the driver side door that controls all of the windows and locks. Could this be a possibility? If so, it would be easy enough to check out.

 

When this condition occured in my old Corolla,I sprayed some penetrating oil down the actuator motor mechanism and it worked. Maybe its seizing up again.