keyless start it doesn't start the car it opens my trunk?

try a new battery in key fob might be a bad key fob. The keyless start and trunk controls are handled through the BCM which sounds like it might be bad but to be sure lets doa CAN scan, 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 a guide to walk you through how to replace the BCM which you can get a rebuilt-preprogrammed unit by searching google or ebay

https://www.2carpros.com/articles/how-to-replace-a-bcm-body-control-module

Below is how to change the BCM out in your car. Check out the images (below). Please let us know what happens.