First, of all I don't think there is any direct way to downgrade that works for Slim PSP 3.72 FW. Second, u need a PSP phat one to create a pandora's battery using the original battery that comes with the PSP phat. And also a memory stick to create the magic memory stick needed for the downgrade. There are tons of websites and webpages around her and ther to help u with how to create a pandora battery and magic memory stick using the phat PSP.

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