Downgrading PSP Firmware 2.85 and below ( FAT PSP Only )

Step 1. If you have version 1.5 Firmware, skip to step 6. If you have a custom firmware, skip this section. Otherwise, Upgrade to 2.80. To do this, create a folder in (/psp/game/update/) and extract the 2.80 eboot.pbp to that folder. Execute the Update program from the PSP game menu.
2.80 upgrade eboot.pbp

Step 2. Grab a copy of the following:
Quote:
1.50 Eboot
Hen D hacked to work with 2.80
2.80 Downgrader
Move everything inside of HEN D’s MS_ROOT folder to the root folder of your psp, such as E:\ or J:\.
Move everything inisde of the Downgrader’s MS_ROOT folder to the root of your psp, such as E:\, F:\.
Rename the 1.50 Eboot.pbp file to UPDATE.PBP, and put it in the (/psp/game/UPDATE) folder.

Step 3. Go to your PHOTO folder, and open HEND 2.80 folder. You should see a flash of blue. If you don’t and it shuts off, try the following:

3.a. Select wallpaper to fill up memory.
(Goto Photo, look at a picture, press /\ and select background)
3.b. Select the HEN D folder with /\, choose slideshow.
3.c. If the above doesn’t work, try turning your psp off and removing the battery.
Replace the battery, turn on, and try again.
To check if the program works, try running the cube demo from your GAME, MEMORY STICK menu.

Step 4. Charge your psp to at least 75%, preferably 100%. Run the program “Update X.YZ” from your Game Folder. You need 75% power or more in your battery. When it finishes, it will ask you to press X. Press X.

If you have firmware 2.81-3.03 psp,
here is how to downgrade to 1.50.

Step 1. Make sure you have a copy of Grand Theft Auto: Liberty City Stories UMD. Then see if it has a 2.00 update on it, or a 2.60. If you have a 2.00 update on that umd, you can do this downgrade! Otherwise, stop here for now.

Step 2. Grab a copy of Noobz’s 3.03 Downgrader here, a copy of 1.50 here, and a copy of 3.03 here.

Step 3. Upgrade to 3.03.

Step 4. Install the 3.03 Downgrader by unzipping it to the root of your memory stick (Like to E:\ or G:\, where your psp is).

Step 5. Grab your copy of the 1.50 EBOOT.PBP, rename it to UPDATE.PBP, and move it to (/psp/game/UPDATE).
It should now be (/psp/game/update/update.pbp).

Step 6. Start GTA. It should get to “loading savegame”, then the screen will clear to black and fill with a light blue color, then the PSP will reset itself.

Step 7. Check that HEN is running by going to “Settings”, “System Settings”, and “System Information”. It should now be “303 HEN”. If not, go back to Step 6.

Step 8. Go to “Game”, “Memory Stick”, and run “Update x.yz”. If your motherboard requires patching, it will be automatically patched, so don’t worry about it. Press “X” to begin the downgrade.

(If it comes up saying that the settings are corrupt, press x to continue. Load the included NetConfigBackup application in your PSP, and select “restore”, this will restore the backup of Network Config done automatically during the downgrade.)

If you have firmware from 3.03-3.50 psp,
here is how to downgrade to 1.50.

Step 1. Make sure you have a copy of Lumines I UMD.

Step 2. Grab a copy of Noobz’s 3.50 Downgrader here or here, a copy of 1.50 here, and a copy of 3.50 here.

Step 3. Upgrade to 3.50. Once this is done, delete the folder (/psp/game/UPDATE).

Step 4. Install the 3.50 Downgrader by unzipping it to the root of your memory stick (Like to E:\ or G:\, where your psp is).

Step 5. Grab your copy of the 1.50 EBOOT.PBP, rename it to UPDATE.PBP, and move it to (/psp/game/UPDATE).
It should now be (/psp/game/update/update.pbp).

Step 6. Start Lumines, and press x to start the game. The screen will clear to black, and fill with a light blue color… then the psp will reset itself.

Step 7. Check that HEN is running by going to “Settings”, “System Settings”, and “System Information”. It should now be “350 HEN”. If not, go back to Step 6.

Step 8. Go to “Game”, “Memory Stick”, and run “Update x.yz”. If your motherboard requires patching, it will ask to be automatically patched, so don’t worry about it. Press “X” to begin the downgrade… DO NOT UNPLUG PSP, TURN OFF, OR TRY TO RESTART.

These next two steps are sorta optional:

Step 9a. If it says settings corrupt, press x to continue… you will have to redo the net connections for the psp, thats all.

Step 9b. You can load NetConfigBackup application, and select restore, which will restore the network settings that existed before downgrading.

These next steps are a tad convoluted. It involves updating to several firmwares, since at the moment there is no single method of updating. Sorry for this.

Step 1. (For 1.50, Fat PSPs.) Go to the below link, and download the “Firmware 3.52 M33″ Zip. Unzip the contents of “1.50only” (kxploitpatcher and kxploitpatcher%) to your game folder (/psp/game/). Activate this program from the PSP game menu.
Dark_AleX’s Firmware 3.52 M33

Step 2. From the same zip file, copy the “M33CREATOR” to your game folder (/psp/game/) so that it is (/psp/game/M33CREATOR/).

Step 3. Get a copy of the eboots to update the psp to 1.5 and 3.52, and rename them to : 150.PBP and 352.PBP.

Place these two files inside the folder (/psp/game/M33CREATOR/). Run the program by going to your game menu and selecting “3.52 M33 CREATOR”.
This doesn’t write to flash, it just makes a file for the updating process.

Step 4. Make sure your psp is charged ABOVE 75% (100 is fine).

Step 5. Go again to Games/Memory Stick on your PSP, and execute “3.52 M33UPDATE”. You’ll have to press X to agree to the installation.

When finished, press X to shut down and reboot manually. Don’t forget, you can’t skip step number 6 if you want to get to the most recent firmware, ok?