Alright, lemme me give it a shot.
Your PSP is sony's Official 3.70 Firnware.
In order to downgrade, you will need to make a pandora's battery or buy one.
In order to make a pandora's battery, you will need a PSP with firmware 1.50 or a CUSTOM Firmware. Or you can open up your battery and mess with the insides to make a pandora's battery.
Once you make the pandora's battery, you need to make a Magic Memory Stick, by sticking certain files on your memory stick.
with the combination of this 'pandora's battery' and 'Magic memory stick' inserted in your psp, it will downgrade to a lower firmware, 1.50 firmware.
The process of making the pandoras battery requires the use of a home-brew app(a home-made application that you can use to play games or whatever) But to play home-brew, you will either need to be on 1.50 or a Custom Firmware.
Hopefully you can understand that
