You can use the pandora battery and magic memory stick to hack it or you can upgrade to 5.03 and run the ChickHEN exploit then run the Hellcats Recovery Flasher to install either 4.01m33-2 or 5.00m33-3. Link for the Hellcats recovery flasher HERE unrar and place the RECOVERY folder in PSP\GAME then after the ChickHEN loads go to Games on the XMB and run the recovery flasher there it will install the custom firmware without the pandora battery.

hi hope you can help i have a psp slim 2003 date code 7c running version 4.00 can you tell me if it downgradeable or not and if not can i use the pandora method and if i can use the pandora method is it best to do the mem stick first or the battery first and is it essential to buy a spare battery or is it just a good idea hope you can help

kieran