For more it looks like a dead end (even fastboot didn't work!), I think you should try one more thing, I'm highly skeptical that it will work, but now I guess every little bit will be something.
First reboot to your recovery. Then plug it to your PC and go to your and folder, now type:
dd if=/sdcard/null of=system
dd if=/sdcard/null of=userdata
dd if=/sdcard/null of=boot
If the command went trough rightly, it will format your system, kernel (boot) and data. If this doesn't work I'm out of ideas, I was going to suggest things that were already suggested here, so it only left me with this. I just want to tell you that if something goes wrong and it stops working, I'm not responsible for it. If the command works, then it's all about flashing a new ROM.
"Time is too short to cry, long enough to try." - March of Time (Helloween)
Sent from my KitKat Nexus 10