its because newer consoles have a minimum firmware version of 3.60 or higher and will never support 3.55 or below sony blacklisted the private key that geohot found in newer firmwares and new consoles also have new boot loader keys so you cant flash a custom coreOS onto a 3000x or higher cause they have been signed with the old bootloader keys.
if by some miracle the new private keys can be calculated then all the new consoles would be jailbroken again but this is highly unlikely now that sony use a true random number to generate them
it won't work anyway cause the 4.30 custom firmware has been resigned using old bootloader console keys, 3000x series has new keys but to bypass the flasher problem extract the coreOS from the 4.30 custom firmware and you need to byte reverse it and paste it into your nor backup at offsets 0C0010 & 7C0010 using a hex editor
make a backup of your console nor data and keep it safe, then download this and open both the download and your nor dump in a hex editor copy and paste the whole thing twice, once at offset 0c0010 and again at 7c0010 then save and extract with flow rebuilder everything should be fine then you will have made your console nor backup have rogero 4.30 coreOS
lol i'm done bricking my console for the time. i guess i'm just going to wait until they fix this metldr.2, i even took the back up of a different slim ps3 on cfw rogero and pasted them over on the 3001, just another brick. its been almost a year now i believe and still no fix for this to be able to downgrade?
i only thought it was just the lowest firmware downgradable to not a metldr trouble. well i hope some one can fix this on these newer models. other than that my tutorial is good for all the older slims and phats to just downgrade straight to 4.30 rogero with out 3.55