2001 Not Starting

On my 2001 Buick Park Avenue, I removed the instrument panel because the fuel guage was pegged. After replacing it with a used one from a junk yard for a 2003 Buick Park Avenue and also replacing the radio with a CD player factory radio (junk yard), I am unable to start the vehicle. Turning the key to on will light things up but attempting to start the vehicle yields nothing. The transmission indicator (Park, Drive, Reverse) no longer functions. I have tried putting the previous two items back in but have had no luck. It started fine before beginning this work. Any help would be greatly appreciated!