The PSP Pandora battery allows you to put the PSP into service mode so that you are able to recover a PSP from a bad flash or downgrade your firmware. The PSP Pandora battery is by far the easiest way to recover your PSP console from a bad flash as well as downgrading. Until now you would need to install chips like the PSP U.P to recover a bad flash, not anymore using the PSP Pandora Battery. It is also worth noting that you can use the PSP Pandora Battery hack on a PSP Slim, having a pre hacked battery is a necessity as PSP Slim cannot run homebrew unless it has been downgraded.
The Pandora Battery is a bulk pack, and it is easy to use: simply insert the magic memory stick into your PSP, then insert the Pandora Battery and follow the simple on-screen instructions. The instructions are also included with the Pandora Battery.
It is for your PSP Slim only,and will fix it 100%.