I'm stuck in the same place. The note in Section 2 step 16 says to follow special instructions if the update didn't work, but the readme from code.google.com that it refers to is no longer there.
But, I managed to find a copy of it here:
http://sacd-ripper.googlecode.com/svn/trunk/readme
Here are the special steps for 3.55. Just tried this and it worked for me.
If the steps above did not work for you, then you are probably on 3.55 already.
You will have to do a recovery menu mode installation:
1: Plug a USB stick into your computer
2: Copy the custom firmware file that you downloaded to a USB memory
stick as /PS3/UPDATE/PS3UPDAT.PUP.
3: Plug the USB stick into your PS3
4: Power down the PS3 through the menu
5: Now press and HOLD the power button, the system will startup and shutdown
again
6: Release the power button, then press & HOLD power again, you'll hear one
beep
followed by two consecutive beeps
7: Release power then follow the on-screen instructions. You're now in the
recovery menu
8: Connect the USB device and select "System Update."
9: Accept Conditions and Follow the instructions
Dave