How can you downgrade a 6.31 version in psp 3001?

Answer 1

Yes, you can't do it.

PSP 6.31/6.35 to 6.20 Downgrader Released

greg | January 24, 2011Davee with a signed dose of downgrading awesomeness! If you're not satisfied with your current firmware (6.31 or 6.35), or homebrew enabler, then downgrade to 6.20 and run Total_Noob's HEN. It's pretty awesome. And when POPs support happens you know you'll want to … unless PRO gets it first.

I'll attempt a downgrade with my PSPgo shortly. I'll update letting you know how that goes. If you're feeling antsy, go for it, by all means giver; however, know this: We aren't responsible if you damage your PSP. Follow README.txt and you should be good.

[How do I use it?]

Copy the "PSP" folder to your PSP. The downgrader is "signed" and can be launched from OFW XMB. You need to copy the 6.20 update to PSP/GAME/UPDATE/EBOOT.PBP and for PSPgo it must be the eflash it is placed on. After setup run the downgrader and follow the onscreen instructions.

[What does it technically do?]

It uses the utility/power exploit to gain kernel access and reboots into the updater with a special PRX running. This PRX uses the pspdecrypt functionality to decrypt the updater PRX when needed. This allows the updater to boot in the newer firmwares.

Update: Confirmed working on my PSPgo - from 6.35 to 6.20 in about 6 minutes. Cheers, Davee!

Video:

Download:

6.31/6.35 to 6.20 Downgrader R1 (it's signed for OFW)

PSP 6.20 Official Firmware

PSPgo 6.20 Official Firmware

- source: lolhax