PlayStation Portable

Step 2: run the CFW installer

Confirm 6.61 first

Do not attempt this step until System Information reports firmware 6.61. Running a CFW installer on the wrong firmware version can fail or behave unpredictably. Keep the battery charged throughout.

Step 2: Run the CFW installer

This step boots your PSP into custom firmware for the first time using an installer such as ARK-4 or 6.61 PRO. On its own this produces a temporary (live) CFW that lasts until you reboot, which is exactly what you want for testing before committing.

Copy the installer

Place the ARK-4 or 6.61 PRO installer onto your memory card in the homebrew location so it appears under the Game menu on the XMB.
Launch it

From the Game menu, select the installer and run it. Follow the on-screen prompts; it will patch the running system and prepare to boot CFW.
Boot into CFW

When prompted, let the installer load the custom firmware. The PSP enters live CFW. You now have full custom-firmware features active in memory.
Verify it loaded

Check System Information; the firmware line should show a custom marker (for example a PRO or ARK tag) alongside 6.61, confirming CFW is running.

This is temporary

If you power off now, the PSP returns to plain 6.61 and you would re-run the installer. Continue to step three to make CFW permanent with Infinity.