Lets get one thing straight first: you cannot directly install any custom firmware on the official SONY firmwares higher than 1.50. This means that you have to downgrade your PSP to 1.50 before you can run any of the installation programs. For certain firmware versions below 3.03, you can directly use a glitch in GTA: Liberty City Stories to downgrade. However for firmwares above 3.03, there is no such way. Instead you have to use something called Pandora’s Battery. This is a modified PSP battery that allows you to boot any code on any PSP, including the programs that will downgrade your PSP. The process is quite long and complicated, so I will not be writing a guide on this blog. However there are many good ones that come up from a simple Google search.

• QJ.Net Tutorial
• MaxConsole Tutorial (with screenshots)
• IRShell Tutorial

You don’t have a friend with a PSP? Well, all hope is not lost. There is a way to physically modify the battery and make it act as a Pandora’s Battery. However it requires you to crack open the battery, and place a pin between two connectors. Some guides that describe this process are here:

• How to create a Pandora’s Battery and Slim MS without a Fat PSP (with Pictures)
• GUIDE:HOW TO MAKE A PANDORAS BATTERY WITHOUT A PSP WITH CFW