i had another go at putting a custom firmware onto a newer 3000x series console this is what i learned. sony added a 2kb file called lv0.2 inside CORE_OS_PACKAGE.pkg in newer firmwares 3.60+ and it is checked by metldr.2 which is what new consoles have. this prevents downgrades and verifies the integrity of lv0. until we can decrypt and resign lv0.2 flashing different coreOS onto the console is not going to work!
A method to install CFW directly on 3.55+ OFW is pretty much impossible as it requires the private keys. We got lucky once, but that was easily patched and I really doubt we will get lucky again, I mean, Sony just can't be that stupid. There are quite a few cryptography methods that been release on the 80s and still haven't been hacked, so uhmm.... Don't wait for a miracle. I don't think getting a flasher now is wasting money.
had another look at this and need to test some stuff on my old console but i think the fail0verflow cospkg doesnt work on new consoles because i took 4.31ofw coreOS and made no modifications i just repacked it with the cospkg tool and flashed my console and it turns off. so if this method works on my old console then sony stopped the cospkg tool working somehow. anyway i will look at this next year