to take it out completely if u can't get the key to work
1)remove the plastic trim around the front of it----it clips in and 2 screws.
2)unplug the switches---dont forget to wire them back up when reinstalling...they can only fit one way, so dont worry
3)unscrew the 4 screws which hold the brackets holding the stereo
4) unscrew old stereo
5) replace with new stereo and wire up correctly
6) reverse process
by the way...we all assume u know how to wire up a car deck