I tried to take the unit out but the cables on the side get stuck.
You don't get the unit to light up to show that it is getting power? I don't recall seeing a fuse behind the unit. Are you sure all of the fuses in the converter power box are good?
I don't have the exact same camper, but after you pry off with a small screwdriver the two long thin sides (top to bottom) and expose the three on each side screw holes, (I only had 3 screws in the 6 holes), the Genesis unit has to be able to slide straight out. There will be a little extra wire behind the unit allowing you to see what is behind the Genesis.
If yours is like everyone's you will not get stereo playback except from the outside speakers, unless you rewire it from the back. As I recall there is a wiring diagram on the back of the Genesis unit. My entire left (or right) channel was not even hooked up to inside speakers.