Noob Tutorial: How to downgrade/flash your PS3 SLIM from firmware 3.70 to 3.55 via ProgSkeet/Teensy++ and install 3.55 Kmeaw CFW - PS3/PS4 Anleitungen - xboxhacks.de - Deutsches Xbox 360 und One Forum
Ps3 won't update regular software from cfw to OFW : r/ps3hacks