:mad1: I had the kernal patch so I tried to go back to 3.52 and guess what? my psp is now bricked with no recovery!!!
WTF I'm pretty mad over here, never should have upgraded in the first place....:mad1:
Well I found out why you bricked. I'm guessing you have a TA-082 or TA-086 motherboard, as going from 3.71 M33 to 3.52 M33 worked fine on my TA-079 PSP.
What happened is that during the 3.71 M33 upgrade, idstorage key 5 is un-patched. When installing the 1.5 kernel, key 5 remains un-patched. If you downgrade to any previous custom firmware version or 1.50 with a un-patched key 5, it will brick.
I figured D_A re-patched key 5 when users install the 1.5 kernel patch to avoid issues like this, but apparently not. However there is a way to successfully downgrade by using Noobz's 3.50 downgrader on 3.71 M33, as it fixes the idstorage keys before downgrading. Too bad I didn't notice this before, but at least it will save others who attempt the same.
Thankfully bricks aren't exactly as bad as they used to be, since you can still recover with Pandora.