3 quick problems

I pushed the electric trunk release button LOL
Seriously though, I remember doing the same. I couldn't get past the X brace either.
I'll add that the fiber insulator board behind the seat back will be brittle and easily broken.

Am I better off to just drill this out and replace the whole guts? Seems like even after getting through the back seat this is kind of a pain in the *** so to speak. I'm not opposed to drilling it if that would be easier, since I have no real attachment to the lock cylinder that's in the car