Stupid question re: Firmware 4.05

[nunasdream]

I just bought a 2nd hand PSP (fat) and it seems to have been updated to the latest 4.05 firmware, if i am correct the 4.05 firmware can't be downgraded to run homebrew or emulators can it?

And if not what options do i have to enable this? or should i sell it and get a PSP with a better firmware version?

[mike_jmg]

yes, if it is a phat it can run custom firmware, but you'll need to use pandora's battery