I think you probably have a bad connection. If you only cut one wire to connect to the push button start, why would everything else stop working. I think you wanted to use the starter wire right? Sounds like some accessory wire is crossed. When I remote start my car, nothing electrical would work, only the necessary crap, but radio windshield wipers, wouldnt. So, I tapped the accessory 2 wire and now I have A/C and power windows when I remote start, but always using a in-line fuse and relay.

 

what exactly is the push button mod?