I am having EXACTLY the same problem. Successfully modded slims and Pharos but this is my first jasper.
Funny though, worked once...booted to freeboot and then freestyle dash. Went to play dead island and it wanted to do an update which I said yes caus Di tough it might be just an update for the game. And nothing since!!!!
Rebuild .bin file more times than I can count and even with latest multibuild that has latest dashboard but still nothing. Xell every time with eject but nothing with power button..
I have read this entire thread and my problems are EXACT and I have four matching Nand extracts so I can't see how I can have a corrupt NAND