Extracting dev_flash3 from NAND dump?

Hello!
I got phat CECHG01 40gb US (spider man 3 bundle).
I did cex-dex-cex (via jig) and lost DRL files.
For the love of Lord, i do not remember which last bluray was played. DRL files (off internet) from same console bundle do not work for me.
Re-marry goes thru ok, but nothing happens - same prohibited error.

Now, my only chance as i see it is to decrypt my NAND flash dump, and extract /dev_flash3/ partition somehow.

Can this be done? Got linux and some exp.

Thanks!