This works on FW 3.55 without a physical dongle.
You should have graf_chokolo's modules, and patches installed.
Use this method to install a lower firmware.
Thanks to graf_chokolo for bringing Linux on PS3, with all its goodies back to the PS3 ==

Downgrade Method - Emulating JIG with Linux[edit | edit source]

1st step – Generating a challenge

2nd step – Generating a valid response for a challenge

You need a dongle ID. Valid range for dongle IDs is 0×0000 – 0xffff. So choose one, it does not matter which one, but some are revoked !!!

ps3dm_usb_dongle_auth /dev/ps3dmproxy gen_resp 0xBABE “here is a challenge like this 0xXX 0xXX … of size 20 bytes”

3rd step – Verifying response (Enabling “Product Mode”)

“here is the response from step 2 like this 0xXX 0xXX … of size 20 bytes”

4th step – Checking if “Product Mode” is enabled

The returned value should not be 0xff.

5th step - Inspect if CORE_OS_PACKAGE.pkg isn't damaged

ps3dm_um /dev/ps3dmproxy inspect_pkg 1 0x9 CORE_OS_PACKAGE.pkg

6th step - Install CORE_OS_PACKAGE.pkg

ps3dm_um /dev/ps3dmproxy update_pkg 1 0x9 CORE_OS_PACKAGE.pkg

7th step – Disabling “Product Mode”

This step is really important, if Product Mode is not disabled you will need a dongle to get out of it

Alternative Downgrade Method - tested and not working[edit | edit source]

1st step – Enabling product mode

2th step – Checking if “Product Mode” is enabled

The returned value should not be 0xff.

3th step - Inspect if CORE_OS_PACKAGE.pkg isn´t damaged

ps3dm_um /dev/ps3dmproxy inspect_pkg 1 0x9 CORE_OS_PACKAGE.pkg

4th step - Install CORE_OS_PACKAGE.pkg

ps3dm_um /dev/ps3dmproxy update_pkg 1 0x9 CORE_OS_PACKAGE.pkg

5th step – Disabling “Product Mode”

This step is really important, if Product Mode is not disabled you will need a dongle to get out of it