Installing 3.71 M33 on 3.52 M33

Requirements:

• PSP Phat with 3.52 M33-3 or greater or PSP Slim with 3.60 M33 (follow this guide if you’re PSP is still OFW)
• PSP battery that’s at least 78% full
• The 3.71 M33 and installation file
• Set the kernel to 3.52: do this by (hard) booting your psp while holding the R button. Go to Configuration, look for the kernel configuration and set it to 3.52

Installation of 3.71 M33 on 3.52 M33-4:

• Extract the 3.71 M33 files to your computer.
• Copy the Update folder to X:/PSP/GAME/ on your PSP’s memory stick.
• Download the official 3.71 update and rename to 371.PBP.
• Copy the 371.PBP to the directory; X:/PSP/GAME/M33CREATOR/ on your PSP’s memory stick.
• Run 3.71 UPDATE under GAME on your PSP
• Press X if asked to correct idstorage keys
• Continue to install the official 3.71 SONY when prompted
• After all process is complete, press X. Your PSP will reboot.
• Congratulations, you’ve just installed 3.71 M33

Now in order to switch from 3.71 M33 to 3.80 M33, you need update 4 of 3.71

Installation of 3.71 M33-2 on 3.71 M33:

• Download 3.71 M33-2 and extract it to your computer.
• Copy the Update folder to X:/PSP/GAME/ on your PSP’s memory stick.
• Run 3.71 M33-2 UPDATE under GAME on your PSP
• After all process is complete, press X. Your PSP will reboot.
• Congratulations, you’ve just installed 3.71 M33-2

To install 3.71 M33-3 and 3.71 M33-4, just repeat the steps above using the files provided. As a precaution, format your Memory Stick or delete all used files before proceeding. After which you can proceed to the next installation.