tutorial on how to make a pandora battery with an origonal psp slim battery (battery that comes with psp):
i do not take responsibility if you mess up your battery. =))
1. you need a psp slim battery, not a psp of another brand. it has to be a sony psp battery.

2. ok, open your battery on the side with something like a knife or something with a flat end, like a guitar pick.

3. then you will see this inside:

4. then lift the circuit board so that it goes out like this:

5. then examine your circuit board.

6. then look for a small chip that looks like this:

and lift the leg.
7. here is a picture of which leg to lift if you are confused:

8. then close the battery and glue it shut.
9. then put the battery back in the psp and it should start by itsself but you will se nothin on the screen, it will just be black.
10. now you have a pandora battery. you now need a magic memorystick.
How does this work?
The pin that we just lifted was actually the ground pin of the EEPROM. Removing this pin effectively shuts off the EEPROM. When the microcontroller inside the battery tries to read the EEPROM, it will think the EEPROM contains all 1s (in binary). This is because of the pull-up resistors on the data lines. So the microcontroller returns a serial number of 0xFFFFFFFF to the PSP, which then goes into service mode.
p.s. it works on a psp phat also but you need to have the charger plugged in for it to work.