Firmware downgrade to 1.50 - Possible Solution

[sagatr]

The following idea is a possible solution on how to downgrade your firmware to version 1.5. You will need the following files and program to perform this downgrade :

1. Version 1.5 EBOOT.PBP
2. pbp-unpacker-0.94

If you install pbp unpacker and open EBOOT.PBP you will notice it contains 4 files. The file we need to modify is PARAM.SFO. If you open the PARAM.SFO files you will see 14 lines of code.

Line 5 is: TITLE PSP Update ver 1.50
Line 14 is: UPDATER_VER 1.50

If you modify the above lines to:

Line 5 is: TITLE PSP Update ver 2.10
Line 14 is: UPDATER_VER 2.10

and save the file PARAM.SFO. Finally you need to create a new EBOOT.PBP using the modfied PARAM.SFO.

You can now use this new EBOOT.PBP and downgrade your PSP the same way as you update. You should no longer get the error "Your PSP does not require an update" as it will think you are updating the PSP to version 2.10.

I have not tested this. I will do so as soon as i get hold of a UK PSP on the first of September which will come with verion 2.0 firmware.

[poison2003]

i think this has been tried and it doesnt work it jsut crashes your psp and you wont be able to use it anymore try to use search button maybe u can find someone who did it and he can tell u

[bill00000]

The new eboot wouldn't be signed by sony, and wouldn't run, just like any homebrew eboot on 1.51+

[grabnak]

Has anyone ever mentioned UMD Movies? I mean, they play on the PSP so they must be signed. Would it not then be possible to then compare lets say a copy of the movie compressed from DVD to a PSP file? All I can think of is that maybe the UMD files (games, movies, etc) are signed with a code that is generated from the checksum (MD5 like) code through an algorithm to create the key?

[therod]

you're all hurting my sides

[cablio]

Since Sony released high security, signatures and checksums (1.51), this won't work or will work only for downgrading 1.52+ to 1.51 wich is not a big achievement for the bet you place.

I don't believe editing a PBP file (or the files in it) will be so easy. Reverse engeneering is not for newbies.