The only other way you can downgrade to v1.50 to install a custom firmware, is to use the pandoea’s battery. But youneed a psp with custom firmware already on it to make a pandora’s battery. So you might as well downgrade your psp by using a downgrader program. Have a look at this guide "HERE". ok, I know it’s on another forum but I can’t find any info or downloads that you can download on here. sorry if I’ve broken any forum rules. But it’s a really good. Loads of people have used it with great success