2.
You get this file from your flash0 ; this option is easier than getting it from your firmware dump.
3.
Get this file from your flash0 and open it with the hex editor and croll down and see if theres any readable text. If you dont see a thing readable; then you'll have to dump this file "firmware dump" and get the decrypted file, I cant tell you for sure because I did this soo long ago that my file is decrypted and I have no idea if I took it from flash0 or I dumped it. But its either one
Good luck!!