Ok guys well today im going to show you how to make a patched 3.55 Core_OS.bin you need for downgrading purposes incase your gonna try you will need to patch a 3.55 Core_OS so i thought i would tell you how and make it a little easier. I have also included at the bottom of the TuT a download link to a 3.55 Patched Core_OS.bin. So lets just go ahead and get started
Things you will need
-A firmware .pkg decrypting tool ( I used Waninkoko's tool but you could also use Geohot's tool)
-MFW builder (used to patch the Core_OS. Sorry about using MFW builder but it's the easiest way i found to get it patched and it works)
1. We need to modify MFW builder so go ahead and open the MFW folder and then open the tasks folder and find the patch_lvl1.tcl file (you can see the file you need to edit in the pic below)
2. open the .tcl file in Hex editor and set search "\x41\x9E\x00\x1C\x7F\x63\xDB\x78\xE8\xA2\x85\x68\ x38\x80\x00\x01" then set replace "\x60\x00\x00\x00\x7F\x63\xDB\x78\xE8\xA2\x85\x68\ x38\x80\x00\x01"
Now that your done modifying MFW builder we can move on to the actual patching of the Core_OS
3.Open MFW builder and only apply the lv1 patch to OFW 3.55. Let MFW create the patched .PUP.
4.Now to get the Core_OS so you can patch it into your NOR dump you need to extract the MFW 3.55 .PUP using .PUP extractor
5. After you extract the .pup you will have a PS3UPDAT.PUP.EXT folder in the same directory as your original .pup file.
6. Now open the PS3UPDAT.PUP.EXT folder and find your Core_OS.pkg it will be in File 7 (like in the pics below) and you also need to get the lvl1.self.
7. Now you need to decrypt the Core_OS.pkg with the decrypt Firmware .pkg tool.(I used Waninkoko's tool but you could also use Geohot's)
8. Now that you decrypted that you need to open both LVL1.self and you core_os.bin in a hex editor
9. Now in hex editor select your whole LVL1.self and copy it.
10. In hex editor switch over to your newly decrypted Core_OS.bin and highlight everything between offset 0x0010fb80 and offset 0x0023661f and then paste in your LVL1.self you copied earlier.
11. Now save that Core_OS. (This is your new patched 3.55 Core_OS that you will use to replace your original Core_OS in your NOR dump)
I patched one for those of you who are haveing trouble making your own download it below.
Alright guys we couldn't make it anymore easy for you to downgrade we have given you a TUT for every aspect of the downgrading process....so go downgrade and enjoy your homebrew.