2004 Infiniti G35

Here is a real crazy thing that is happening to me. I installed an aftermarket nav in my car which replaced the bose sound it work perfectly for months. I then decided to add on an xm tuner. I installed it and when I turned the ignition off EVERYTHING in the car stayed on with the exception of the a/c. I thought that the ignition connection in the harness had come loose so I took apart everything and rewired it. When I reconnectend everything the radio did not work, along with stock nav still in the lcar. Also the instrument panel lights do not work. And also the check engine light came on, and never was before. I checked every fuse in the car and nothing is burnt out. What on earth can be the problem!