I'm really not familiar with PSP homebrew, but here's what happened: I was transferring ISO games from my computer to PSP in USB mode when suddenly, the memory stick became corrupted. So I reformatted it both on the computer and on PSP, but the PSP won't recognize it. I then used a memory card reader to reformat it again, then it on the PSP, and it can be read again. Transferred some games (now via memory card reader), and all the corresponding icons appear on the game list (even the thumbnail movie and background changes when selected). But after the PSP logo flashes, the screen would go black, then the device shuts down by itself. I even reformatted the PSP but the same still happens. The firmware by the way is 5.50 Prome-4. Can anyone please help me? Thanks in advance.