Use Rogero 3.55 downgrader.
http://www.mediafire.com/download/4bhuz73u42o8rj9/3.55_Rogero_Downgrader_RSOD.PUP
Make sure you enter recovery mode to install this though mate
Here’s what you need to do to boot your PS3 into Recovery Mode…
Step 1: Turn off your Playstation 3.
Step 2: Hold the Power button down. The system will turn on and turn off once again.
Step 3: Once the system has been shutdown, press and hold the Power button again until you hear 2 consecutive beeps.
Step 4: When you hear the 2 beeps take your finger off power button. You will be prompted to plug in your controller via USB and then press the PS button. The Recovery Menu will pop up.
Then use option 6......'system update'