Extract the download. You will see folders: PROUPDATE , CIPL_Flasher , and FastRecovery . Copy all three folders to PSP/GAME/ on your Memory Stick. On your PSP, run from the Game menu. Press X to install. Once finished, you are on 6.60 PRO-C2! Phase 4: Making the CFW Permanent (CIPL Flasher)
Some older CFWs, like 5.00 M33-6, will spoof their version number to 9.90 to prevent accidental updates. When you try to install a 6.60 OFW, the PSP will see "9.90" and refuse to update because it thinks it has a newer version. To fix this: psp 352 m33 upgrade to 660 portable
Once finished, reset your console. Your PSP will now be running 5.00 M33. Step 3: Installing Official Firmware 6.60 Extract the download
Format your memory stick directly from the PSP interface under > System Settings > Format Memory Stick to build a clean directory path. Stage 2: Install 6.60 Official Firmware (OFW) On your PSP, run from the Game menu