Hi! If many mechanics have tried to troubleshoot your issue with the car right in front of them, and they haven't been able to resolve it, you're going to have to provide a lot more information about the car and what's happening with it for non-mechanics/users on an online forum with no access to your car to even attempt to help. All that is known so far is that you have a 2013 CX-5 with an engine that has been swapped out.
For example - What engine did the car come with, and what engine did you replace it with? Was the replacement engine known to be working? Who performed the engine swap, and why aren't they troubleshooting this issue for you? Why is "theft detect" in your title? What region of the world are you in? When your mechanics looked at the car, what did they attempt to do to fix the no-start issue? Aside from having other mechanics look at the car, have you tried to resolve the issue yourself? The list goes on.