I got slim Psp
I made Pandora battery and magic m stick my self
and I downgrade 5.02 ofw to 3.71 M33 Cfw sucessfully
again i want to downgrade 3.71 M33 cfw to 1.50 so

what i did is
open magic mstick from psp
there were 3 files and 3 folder
folders: Kd, PSP, Registry
Files :150.PBP,371.PBP,msipl

I deleted 371.PBP and chage name of 150.pbp

and installed sucessfully

but when i reopen there is black screen psp doesnot Starts why??
can you plz help me