6.3XX and 6.6X Custom Firmware Update Guide
If your PSP is currently running a 6.3X or 6.6X Custom Firmware (PRO or ME) it is recommanded to do a clean Official Firmware install before updating to the 6.61 Ark-4 Custom Firmware.
Mandatory
For Custom Firmware using Infinity ∞ as a permanent patch it is MANDATORY to follow do this! You will BRICK your console otherwise!
Follow the guide below to clean install the 6.61 Official Firmware with Chronoswitch Downgrader.