id say for fat psp 3.80 is the best right now. you need a pandoras battery, you can but one or hard mod an original battery (popping off the fifth pin inside it) making sure you have another of course, seeing as you cant use it for a reg batt when ur done with it, itll always be a pandora. uhhhh....u then need to download the totalnewbie pandora installer or something like that off the internet, google it. download it to mem stik and put in pandora and itll downgrade it then get cfw and ofw from a site you can find and upgrage to 3.80 M33-5.
hope this helped, contact me if you have specific questions.