I Need Help Downgrading Psp Slim 3.90m33-2 back to 3.71 m33

I upgrade my psp slim to 3.71m33 to 3.90 m33-2 and now i relize that it kinda suks can enyone help me downgraded and tell me the way that i dont have to use pandora battery or magic memory stick. also does anynone know how to create a pandora battery with psp slims battery

you can only do it using pandora and a magic memory stick

I don't know how to create a pandora with a slim
I think there is a plugin or something