The rear liftgate will not open?

We need to check the six fuses that run the system , you have three inside the interior fuse panel and three in the fuse panel under the hood, here are the fuses that run the system in the images below and I have included the wiring diagrams so you can see how the system works.

This guide can help you check the fuses:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Also, I would swap out the batteries in the remote to see if that fixes it. Check out the images (below). Please let us know what happens.

When you say it opens manually, does this mean you must lift it up or the motor lifts it when you use the key manually? If you need to help or lift the lift gate yourself chances are the lift motor module has gone out, but to be sure we should do a CAN scan to see if any of the body codes come up. You can get a CAN scanner (Controller Area Network) which will work on most cars from Amazon.

Here is a video to show you how:

https://youtu.be/u-4syLc-ifQ

and

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Here is how to change the unit out. Check out the images (below). Please let us know what happens.