Well if it is a NON-TAv3 board yes you can use Pandora to downgrade. If not nope your stuck for now till someone finds a way. You can use homebrew using the latest HBL but no ISO loading that is for sure. There are "signed" PSP games floating around that will work just fine on your PSP as they require no mod at all as the PSP see's it as official Sony software from PSN network.
PS3 CECH-25001 Rebug 4.41.2 "Lite" 1tb iNt & 2tb eXT mM 4.40.00
Back online thanks to Primee for the legit PSID!!