Downgrade/unbrick any PSP with 3.52 and below. You just save it to your desktop/disk and then run the program and it will guide you to a very simple installation and you will have a Pandora Battery in about 5 minutes.

Keep in mind you need to use a PSP with cfw so you can create the battery (like everyone says-borrow a friends) then the battery you have inside will become a Pandora´s and will only be able to unbrick your PSP or downgrade it. YOU CANNOT USE THE BATTERY TO PLAY A GAME. IT WONT WORK!!

Once you have the battery made. put it in the PSP you want to downgrade and follow the instructions you should have a 1.50 PSP when your done.

Be sure to read the read-me file.