What is your current firmware?

I havn't tried this, this isn't tested, but I guess you can try. Remember I havn't tested this. And if this doesn't work, then I guess you have to get a Pandora Battery and a Magic Memory Stick.

*REMEMBER, THIS HASN'T BEEN TESTED, SO IDK WHAT WILL HAPPEN*

If you have OFFICIAL SONY Firmware lower then 5.00, then you can download these two files:
500.PBP: http://rapidshare.com/files/154173870/500.PBP
5.00 M33-6 EBOOT.PBP: http://www.megaupload.com/?d=PLU7DL0N

After downloading the 500.PBP and the 5.00 M33-6 Updater, plug your PSP into the computer via USB cable and cut/copy and paste the 'PSP' folder in the root of your memory stick. Then cut/copy and paste the 500.PBP in ms0:/PSP/GAME/UPDATE. Then after that, disconnect the USB Connection and run the EBOOT.PBP from your XMB. It will not say EBOOT.PBP, I forgot what it says, but you will see an icon of a 5.00 M33-6 Update. Run the update, and just wait a couple minutes, and your done =P

Rep+ if this helped.