There's a universal unbricker release that does 3.71M33 now. Universal meaning that it works for both the old and slim psp. I tried it myself, and it works perfectly fine(although on the slim since you can't see any menu it was all guess and check). The one downfall though, is that I am unable to run the Pandora Battery Creator on my 3.71M33 firmware to restore back my battery, so I had to borrow my friend's 3.52 to convert it back to normal.
*edit* forgot to mention that i was trying to restore using my 3.71M33 old school psp. that's the one coined as "phat" right? :X
*edit* forgot to mention that i was trying to restore using my 3.71M33 old school psp. that's the one coined as "phat" right? :X