| what do you wanna downgrade to 1.50 for ?
did you extract the "flasher for recovery folder" contents to your psp giving you the folder psp\game\recovery which contains 4 files (before usage) then get a 1.50 sce update eboot.pbp and rename to UPDATE.PBP and copy to the psp\game\recovery and then run it. these are the steps i used to downgrade to 1.50 and it was sucsessful.
p.s. any modding?
__________________ Black PSP 2.71 SE-C EU 
Black PSP 3.71M33-2 EU
Black Slim PSP 3.71M33-2
Nintendo DS + M3dssimply
Nintendo Wii + Wiikey
Xbox Self Chipped, Xbox 360 NME Self Chipped
Ps3
1GB Sandisk MS Duo, 2GB Sony MS Duo, 4GB MS Pro duo, 4GB Datel Harddrive
Grand Theft Auto LCS
Grand Theft Auto VCS
3600mAh External Battery
+Plenty of Homebrew |