Impressive Homebrew will allow us to lower our PSP 6.XX almost any version 6.20 (or less, if your PSP supports it), either to repair small errors Flash0 or just out of curiosity. We recall that to downgrade is extremely risky, we should follow the instructions to the letter or we can leave our PSP completely useless.

Official Website.

http://psp.scenebeta.com/noticia/chr...tch-downgrader