I've been searching OJ and various other sites looking from a tutorial on how to downgrade my "fat psp" from 3.52 M33-2 to 1.50 (official firmware). I hope someone can help me. The reason i want to downgrade is because i want to play my backed up ISOs via USB and 3.52 M33-2 doesn't seem to support that, but 3.40 OE does. Please correct me if I'm wrong. Hope someone can help me!