1. Insert PS Jailbreak device that has been reprogrammed as PS Downgrade into your console
2. Turn on the console using the same boot method as PS Jailbreak: Press power then immediately press eject. Your console will turn on and PS Jailbreak will light up with red/green LEDs followed by green only, then the PS3 will turn off.
3. Turn on console to make sure you are in factory service mode. You will see a huge red box on the screen saying Factory Service Mode. Once confirmed please turn off console and remove PS Downgrade Dongle.
4. Program any blank USB mass storage device with 2 files:
1. the modified 3.41 PUP
2. Lv2Diag.self (rename Lv2diag.self.1).
These must be the only files on the USB key and must be placed in the main (root) directory.
5. Insert this USB mass storage device into the USB PORT
to the right — the first USB port in from the right side if you’re facing the console. Turn the PS3 on and you will see black screen but the PS3 HDD light will flash.
6. Wait 3 minutes for the system to install the old firmware. Towards the end the power button on the console will start flashing green and then your console will power off.
7. Remove the USB key and turn on the console, you will still be in factory service mode. Please verify you have downgraded successfully to version 3.41.
8. (Optional) – If you wish to downgrade to any older firmware you can follow step 4, 5, 6 using any regular firmware PUP. (You do not need to use modified custom firmware now that you are on 3.41).
9. Insert USB key back into your PC, remove the PUP and Lv2Diag.self file, and copy only the other LV2Diag.self (rename Lv2diag.self.2) to the USB key.
10. Power on your console, after 10 seconds it will power off
11. Turn on your console again with no USB inserted and you will be out of factory service mode and back in retail mode with your chosen firmware version installed.