Downgrading to the version 3.55 system update on your PlayStation 3 is an essential step when attempting to jailbreak your console. Many jailbreak programs are not compatible with newer versions of the PlayStation system operating software. Downgrading your PS3 is considered a violation of your terms of service with Sony and will void your PS3 warranty and may revoke your ability to log on to the PlayStation Network.
Download PS3UPDAT.PUP and Lv2diag.self onto your computer, and save them on your desktop.
Plug the USB Storage Device into your computer and load the PS3UPDAT.PUP and LV2diag.self files onto it and remove it from your computer.
Unplug your PS3 from the power supply and plug the USB storage device into the rightmost USB port on your PS3.
Plug your PS3 back into the power supply and press the "Power" button to turn on the PS3, and load the Factory/Service mode.
Press the "Power" quickly followed by the "Eject" button to turn off your PS3. Press the "Power" button once more to install the downgrade and remove the USB storage device once the process is complete.
Downgrading your PS3 can have unpredictable results. Attempt to downgrade or jailbreak your console at your own risk.