So I go to my car this morning and open the door as I normally would by pressing the button on the handle and sit in the car. I press the brake and push the start button but nothing happens. The car won't even switch to accessory. I dock the key and try again. Still no luck.

I lock the door and run back to the house to grab my other iKey. I run back out and unlock the door (again using the proximity feature). I get in the car, press the brake, and push the button. Still no luck.

Has this happened to anyone before? What is the problem? How can I fix it?

sounds like the car may not be in park? Did you try to move the shift out of park and then back in?this could be a broken sensor

I doubt the problem is related to the vehicle being in park because it would at least switch to accessory or ignition on... there is a fuse in the inside fuse box i believe that says "push button ign" or something like that...if the fuse is not in there check the main fuse/relay box under the hood... i know there is a push button fuse... check to see if its blown and needs replacement. Remember to use the same amp as the old one if replacement is needed.

I'm not sure what the issue was but my car started when I tried again an hour later. I'd still like to know what caused the problem in the first place.

If it's not a fuse , then it might be your Brake assembly switch . This happened to my girls Altima a few months ago. It get worse as time goes by and then your car wont start at all. Should be covered under warranty..