As you have all proberly seen. Today an awesome event took place, this was the release of the Pandora setup files.
Basically, its an app that, takes the 1.50 update and places it on your chosen MS (not full 1.50, but enough to boot PSP to XMB). Once thats done, that MS is now the "MAGIC MS". There is another program that then, rewrites your batteries serial to that of a sony unbricker battery.
You can then take both the battery and ms, and place it in any bricked PSP, turn it on and it will give you a menu, tell it to downgrade to 1.50 and ta da, you have 1.50.
It can also be used to downgrade any version PSP.
I risked my beloved PSP to test and it works flawless.