Many thanks to Rogero for making this guide, it's a mirror of it

i'll be updating it as it's updated here:
http://www.tortuga-cove.com/forums/viewtopic.php?f=127&t=3654After Testing with some bricked Slim consoles ( from updating to CFW4.21 ) with different friends and testers around the world,
I can confirm that Bricked consoles can be recovered back to CFW3.55 even if you didn't have a NOR Dump/Backup .
Requirements are:
1- a Hardware Flasher so you can read/write to the PS3 NOR flash
2- A Dongle with PSgrade payload (any old jailbreak dongle + PSGrade hex will do) used to Enter Factory Service Mode (FSM)
3-
Rogero CEX-3.55 CFW V3.7 Recovery Procedure :
1- Dump the current NOR Flash of the bricked PS3 at least 3 times using a hardware flasher (Progskeet / E3 / TEENSY++)
2- Verify that it is properly dumped and you have a valid dump by comparing your dumps or following these steps --->
Validating_flash_dumps3- Patch the dump using Rogero PS3 NOR Auto Patcher --->
PS3_Nor_Dump_Auto_Patcher_v0.01.rar 3- Flash the Patched Dump back into the PS3 NOR using the Hardware flasher.
4- From this point you can continue as a normal Downgrade Procedure by entering Factory Service Mode using the dongle and Flashing Rogero CEX-3.55 v3.7 from the USB stick.