i need to ask a few questions on haxking a slim psp.. i only have the phat an my brother wants hid haxked but doesn know how..

1) can i use my phat pandora battery for a 1001 to hack a slim psp?

2) his psp is on 5.51.. is it still or currently able to hacked?

3) if anyone has a guide strictly for hackng a 2000 i would help alot.

i havent done this in a lng time and dont really want to mess it up for him. i rep for help givin. thanks.