OK, so we all know about how the original Waninkoko firmware broke the older large NAND consoles, that was due to him overwriting some portions of Cell-OS Lv2 and the segment boundaries, god knows about the signature also. He also zeroed out a good section of the kernel, and also breaks some NAND consoles due to that. Now, you want to fix this issue? Well, you have to have:
1) A NAND Dumper
2) CORE_OS_PACKAGE.PKG patched to remove signature checks or Official Core OS/PS3 in Service Mode
3) A NAND Flasher
4) Flow Rebuilder
5) Hex editor
6) PS3 with firmware less than 3.55
OK, so you first have to dump both NAND chips (2 128MB NANDs for a total of 256MB) and interleave them using Flow Rebuilder, then decrypt the CORE_OS package to give you a raw core OS image, then open your combined NAND dump in a hex editor and search for “6F FF E0″ in the search for hex section. Once there, you should see:
00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 6f ff e0 |.............o..| 00000010 00 00 00 01 00 00 00 17 00 00 00 00 00 6f ff e0 |.............o..|
Right after the second “6F FF E0″, remove the next 7,340,000 bytes, then, insert the unpacked Core OS (7,340,000 bytes). Then split the image using Flow Rebuilder (use ECC!) and flash. Hopefully it should work, and then you can just Lv2diag your way out.
Do not overwrite anything else.
This guide should help you fix any NAND console with Core OS fail.