I recently got a used PSP to try some homebrew applications.
To enable homebrew you have to downgrade from the official firmware using some kind of an exploit. There are different kinds of exploits depending on what firmware version you are going from.
This method is using the Grand Theft Auto Libery City Stories exploit to execute the 2.60 to 1.50 downgrader. From that point it's possible to upgrade to a new custom made hacked firmware, in this case the latest M33 3.52 firmware.
- Download Downdater Auto Final for 2.50/2.60.
- Put DOWNDATER FINAL AUTO EBOOT in the /PSP/GAME/ folder on the Memory Stick
- Download DOWNDATER.rar (sear for it). It contains the already extracted 1.50 firmware files needed. Normally done using Downhelper on a 1.50 machine, but since that's hard to find another PSP with 1.50 get that rar archive.
- Download eLoader 0.9.9.5 or newer zip or installer.
- Install the eLoader files into /PSP/GAME/. This includes the GTA exploit.
- Insert the GTA UMD and run the game
- Wait for the eLoader menu system to load and execut the Downdater Final Auto from the list.
- The screen will be black but the Memory Stick light will flash. This means the flashing proceedure is running. Leave it alone for a few minutes untill it asks you to reboot.
- At the first startup a message about corrupted config will be displayed, press O.
- The PSP is now running 1.50 and able to execute all homebrew applications located in the Memory Stick directly.
- Download the M33 3.52 firmware pack
- Put kxploitpatcher and kxploitpatcher& into the /PSP/GAME/ folder
- Go to the Memory Stick PSP menu and run the KXploit Patcher to not require the spesial %-folder to launch an application
- Download the official 1.50 and 3.52 PSP firmware and rename them to 150.PBP and 352.PBP respectively, put them in the M33CREATOR folder
- Copy the M33CREATOR folder to the /PSP/GAME directory
- From the Memory Stick menu, launch the 3.52 M33 CREATOR application. It will exit back into the menu after it's finished writing the new files.
- Again from the Memory Stick menu, launch 3.52 M33UPDATE this time.
- The PSP will now be flashed to M33 3.52.