Rear doors not locking/unlocking

On my 2008 CX-9 Grand touring, both rear doors slowly started to not work. At one point they would unlock half way (but wasn't unlocked). Now it's gotten to the point that they will not lock or unlock now unless I manually move the locks.

I tried replacing batteries on remotes, locking unlocking the car with the key, and using the drivers lock mechanism. Nothing will trigger them. I have to slide my hand in and unlock/lock them.

Anything I can do solve this on my own before going to the stealership? I'm afraid of some electronic replacement that will cost 2 grand and end up being a stupid thing I could of done.

Since they gradually stopped working over time, I would suspect it's a mechanical issue rather than an electrical one. There are 2 actuator cables in each door and given the age of your vehicle, they most likely need to be lubed.

I suggest getting the factory service manual which has been posted on this site, just search for it. You will have to remove the interior door cards to access the cables. If that doesn't solve the issue then it's probably electrical. For that you will need an ohmmeter to check the voltage across the switches.