My brother just went through the same thing. I feel bad for you, but I will tell you, 3 months after the surgery, he is much better, so hang in there.
If absolutely nothing works, are you sure the battery isn't dead? As far as the key from online, that needs programmed by a dealer or someone that has the software to do it. If it isn't done, the car won't recognize it.
Have you tried charging the battery just to confirm that isn't an issue and are the battery terminals clean and tight? I noted you replaced the battery, but I thought that was in the fob, so that's why I'm asking.
Also, if the battery in the car is good, there are two fuses that are mounted to the positive battery cable. These are high amperage fuses. Check them to make sure they are not blown. If you look at the attached pic, you will see they power nearly everything.
Here are a few links you may find helpful when testing:
When you check the fuses, even if they appear good, make sure there is power to them and out of them.
Let me know if you have questions or need anything.
Tuesday, April 7th, 2020 AT 8:03 PM