i have a 2002 cadillac deville. i replaced the factory radio with an aftermarket indash tv. however when i re-installed the factory radio, it failed to work. when i fist turn the key and press power, it turns on like its going to work, then shuts back off. however the clock still shows, so i know its getting power. it doesnt display and error code or lock on it. why is it doing tis? and how do i fix it?