Replacing PSP system files with old PSP system files?

-Alright...well...I had bought a Red PSP, 2001 from a friend a while back.(God Of War Edition) And it had CWF on it, with all these games and sh*t. And then I had bought Kingdom Hearts and I wanted to play it...so me...being a dumbass, accepted the change Sony wanted me to do so I can play the game (Going from 2.00 to like 5.03) And then I couldn't play NONE Of the games...it liked deleted everything...and now I miss playing the games...:/ But the good thing is, my brother has ALL the old PSP files. EXACTLY how it is when I got it. So my question is...what if I copy ALL of the old PSP files that my psp had...and delete (or move) the and updated ones I have on my PSP...will it brick my PSP? Or will have I have 2.00 CWF again? Currently I have 6.37...I think the PSP has a Pandora Battery...? (It had to had if it was hacked?)