The 1.50 Downgraders in this post are only for 'fat' PSP systems.
The 'M33 Installer and update' files can be used to install and update Slim PSP already on custom firmware.You can downgrade any PSP Firmware version using the Pandora Battery.
'Pandora' can update ANY Official or Custom Firmware version:
e.g Official 3.71, 2.81, 2.50, or custom firmwares 3.10 OE, 3.40 OE, etc.
If you have a Slim PSP or an Original PSP with Official Firmware 3.51 or higher
you will need to use 'Pandora Battery' to Install Custom Firmware,
There are no Downgraders for slim PSPs or firmware versions higher then 3.51.
Read the "Gathering information about your PSP" Section for more information about
what you need to do to downgrade and install custom firmware onto your PSP.
You will need winrar to extract the files you download from this topic.
You can download the winrar for free here:
WinRAR archiver, a powerful tool to process RAR and ZIP files/!\ Warning: /!\
Upgrading / Downgrading your PSPs firmware will write to the 'flash memory' of your PSP.
There is a very small risk of bricking your PSP when writing to flash memory.
All downgrades should be successful if you follow the instructions carefully and correctly.
Although you may be one of the unlucky few that the downgrade fails on.
By following this guide you understand the risks you are taking with your PSP.
Formatting your memory stick will erase 'everything' on it.
Please make a backup copy of any important files to your computer before you continue.
(Like the savegames in your \PSP\SAVEDATA\ folder and any video / music / pictures you may have.)
Note: After installing the required files to your memory stick, wait for about 1 minute before closing the
USB connection and disconnecting the USB cable, Sometimes windows will keep the data in memory
and will write that data to the memory stick even after the installation looks like has successfully finished.
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What is Custom Firmware??
Custom firmware replaces your PSPs official firmware but it is not a permanent upgrade.
You can easily uninstall the custom firmware and to back to official firmware if you
don't like or don't want to use custom firmware anymore.
Custom Firmware has all the features of the official sony firmware, but also adds the ability
to load homebrew PSP ISOs and PSX EBOOTs directly from the game menu in the XMB.
so you can still play your original UMD discs, Music and Videos using custom firmware.
Custom Firmware also has an option to use 'No-UMD Mode' so you can run your PSP ISOs without a UMD inserted.
The 'Sony NP9660' No-UMD mode has the highest compatibility rate and almost all ISO games work with it.
If you have any PSP ISOs in 'DAX' format, you need to convert them to ISO or CSO files using UMDGEN,
Custom Firmware doesn't support the DAX format.
Your PSPs UMD Drive should be empty while upgrading / downgrading your PSP.
(except when downgrading from 3.03 & 3.50 you will need a UMD inserted to start the downgrader)
It is recommended to remove the UMD Disc from your PSP before you do anything in this guide.
If you don't have a USB cable but you have a memory card reader, you can use that instead.
when you see 'connect your PSP to your computer and make a USB connection',
Turn off your PSP, take the memory stick out of your PSP and insert it into your memory card reader.
When you see 'close the USB connection and disconnect your PSP from your computer'
Take the memory stick out of your computer and insert it into your PSP and turn your PSP on.
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Contents of this topic:
Gathering information about your PSP:
Checking your PSP Firmware Version
Checking your PSP Motherboard Model
What should I do next?
Upgrading / Downgrading Firmware:
Updating your PSPs Firmware
Downgrade 2.00 to 1.50
Downgrade 2.71 to 1.50
Downgrade 2.80 to 1.50
Downgrade 3.03 to 1.50
The 3.03 downgrader requires you to use an 'unpatched copy' of Grand Theft Auto : Liberty City Stories UMD
to start the downgrader. The unpatched copy of the UMD has the 2.00 firmware update on it.
Downgrade 3.11 / 3.50 to 1.50
The 3.11 / 3.50 downgrader requires you to use a Lumines UMD to start the downgrader.
Installing M33 Custom Firmware:
5.00 M33 + Update 4 NEW!!
5.00 M33 1.50 Addon Files
Using the 'Custom Firmware' Recovery Mode
Configuring 'Custom Firmware'
Reinstall / Uninstall 'Custom Firmware'
Help with using 'Custom Firmware':
Mini Guides:
Installing PSP ISO games onto your PSP
Installing PSX EBOOT games onto your PSP
Installing Homebrew onto your PSP
Putting Music on your PSP
Putting Videos on your PSP
Putting Photos on your PSP
Customize your PSPs Background Picture
Joining Multi-part Rar Files
Converting Between ISO and CSO formats
Error messages you may get while running 'Custom Firmware'
The game could not be started. (80020321)
The game could not be started. (8002014C)
The game could not be started. (80020130)
This disc cannot be started. The region code is not correct.
Connection Error: The WLAN switch is not turned on.
How do I....
Stop the UMD from Auto-starting when I turn on my PSP?
Enable the flash player and WMA playback without wireless internet?
Switch the "Confirm" and "Cancel" buttons used in the XMB?
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Gathering information about your PSP
Checking your PSP Firmware Version
First you need to check what firmware version your PSP has:
To find your PSP firmware version:
1. In the XMB scroll to the left to 'Settings' (XMB is the main menu of your PSP)
2. Scroll down to 'System Settings' and press 'X'
3. Scroll down to 'System Information' and press 'X'
4. Your firmware version is what is written next to "System Software:"