Remember this? Well the same person has been in contact with an Italian team called DiGiTaLAnGeL and through twitter they have announced that they managed to downgrade a PS3 slim from 3.70 down to 3.55 CFW using the well known NAND/nor flasher Progskeet. This looks like good news for the scene and people stuck on 3.70. They have said that a tutorial will be released soon.
Originally posted by another user
For the first time, we have been involved in something truly spectacular
We were the first in the world to test the downgrade from 3.70 to 3:55 on a PS3 Slim (With flash memory, ” NOR “

using the ProgSkeet and patched some files provided by dospiedra, a famous Spanish coder already discovered on the crest of the wave for the method of going back to 3:55 / 3:41 with the PS3 (FAT flash memory “NAND”

.
After several attempts, in collaboration with dospiedra, we got to go back from 3.70 to 3:55, enter the factory mode with a simple key to jailbreak, rifleshare a modified version of 3:55 to prevent the SYSCON (the registry in between downgrades) was consulted during the downgrade and now we are happily at 3:55 KMEAW!
With this version of moddata 3:55, you can perform a memory dump today and you can switch on the fly from 3:55 to 3.70 without having to make all this long procedure times: progskeet using it you can go straight to 3.70 changed to 3:55!
Dospiedra said it will release details on the patches applied to the NOR and the update file as soon as possible.
New life for those who arrived too late to enjoy the benefits of the 3:55?——Google Translate
and for whoever said i didnt want to post source my computer shut off and it barely saved so stfu