It's quite easy. Do you still have all the stuff you needed to upgrade to 3.02 OE-A? If you do, rename the folder called 302oeflasher (the one without the %) to RECOVERY, then move it to the PSP/GAME folder, if it's not there already. Then enter recovery mode, and select the option on the menu called omsething like 'Run program at PSP/GAME/RECOVERY/EBOOT.PBP'. This will get your PSP back to 3.02 OE-A, but it should work as normal now.

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