It is a well known limitation that recent PSPs cannot be downgraded below the firmware they shipped with. For example if you bought a PSP that initially had firmware 6.35 on it, you can’t go below that firmware (the real limitations are a bit more complex and motherboard-related but that will do for this article).

You can’t for example, go down to firmware 6.20, a firmware that many people enjoy because it is (for now) the last firmware on which some PSPs can install a permanent Custom Firmware (by opposition to a Light Custom Firmware which gets “uninstalled” every time you turn the PSP off, a limitation that some users don’t really like).

So, the rule was that recent downgraders wouldn’t let you go down to firmware 6.20 if your PSP motherboard is of type “9g”… this is going to change soon, as Davee announced (here and here) he has a Beta version ready for a downgrader that allows these recent PSP models to downgrade to firmware 6.20. This is still under testing but I am assuming it is just a matter of hours before we see a release. Thanks Davee! 🙂