After looking at this thread i tried my own stuff but the same black screen, although i gave readme.txt a thorough reading an found this:
NOTE : You need to remove the signature check for unsigned FastFiles to load.
How to remove the signature check
Signature : 2C 8E 00 00 40 86 FE F0 82 C1 00 80 2F 16 00 01 40 9A FE E4
Replace : 60 00 00 00 60 00 00 00 60 00 00 00 60 00 00 00 60 00 00 00
Edit: After much research (10 mins LOL) i found this:
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Here choco explains that when you modify a FastFile the RSA becomes corrupt and you need to patch the RSA checks on EBOOT.BIN (i think this also means that you can only do FastFile mods on CFW)