Can you downgrade a 3.71 regular to 1.5?

I am new to all of this. I just upgrade my original PSP to the 3.71 and I want to know is it possible to downgrade it to the 1.5. I am hearing thing about making a Pandora's battery and stuff but what exactly is that? Please don't redirect me to some website forum because I can't find nothing on them. Can someone please give me a step to step guide on how to do this? Do I have to upgrade to 3.71 M33 then downgrade to 1.5, or what? Like what do I have to do for me to accomplish this.

Can you downgrade a 3.71 regular to 1.5?windows server 2003

wow i tried sooo hard for it but its almost impossible...dont no wat to tell ya srry