Jailbreak PS3 Slim or Fat on Firmware 4.88 or Lower And install CFW 4.88 - YouTube
PS3 custom firmware installation (fat CECHA01, and slim CECH-2101A) - William Quade
Fat PS3 Firmware 4.82 for Sale in Doraville, GA - OfferUp
I purchased a PS3 backward compatible from ebay for a good price and I'm impressed how clean it is. However... It's still on firmware 2.50. Should I update the firmware? : r/PS3
How to bypass update 4.86 on ps3 fat? Has firmware: Cobra 8.01, and mmCM Version 4.85.01 : r/ps3hacks