There is a constant war going on between Sony and Hackers. Downgrading your PSP and updating it with custom firmware helps you to run the Homebrew hack and install ISOs of different games on your PSP. These steps work for both PSP 1000 and PSP 2000.
Requirements: PSP, Pandora’s Battery, Magic memory stick compatible with your current firmware version.
Follow the given steps to downgrade your PSP:
Turn off your PSP and replace your original battery with the Pandora Battery and your original memory stick with your Magic memory stick. You can either buy these things online or even create your own.
Hold the ‘UP’ button on your PSP and switch in on. You will reach a mode where you will be given the option to install the latest Custom Firmware M33. You can easily choose the required option (generally the first) and install the custom firmware. Press ‘X’ to Reboot your PSP when installation is complete.
When the PSP restarts you have the latest firmware. Now you will update it to the latest update. Go to your memory stick and install the latest update i.e., currently Custom Firmware 5.0- M33(6).
Enjoy downgrading your PSP.