thanks very much for this guide. i bought 2 psp slims for my sons. i was really confused at the beginning but turn out just well. i bought another battery and followed the instructions. the hard part was opening the battery. after that its just a piece of cake. now i have a pandora battery thanks to the thread starter. my installation was 3.71m33 > 3.90m33 > 4.01m33-2.