HOWTO for backporting ps4 games from 6.72 to 5.05

1- orbis-pub-cmd.exe img_extract --passcode 00000000000000000000000000000000 "GAME.pkg" PATH\
Note: passcode is 32 zeros
Example:
\BackPort>orbis-pub-cmd.exe img_extract --passcode 00000000000000000000000000000000 "D:\Games\ps4\RESIDENTEVIL_2_Remake\RESIDENT EVIL 2 (CUSA09171) [v01.04(U)].pkg" D:\Games\ps4\RESIDENTEVIL_2_Remake\
[Warn]  Output of the command may contain confidential information.
[Debug] Image extract succeeded.
(This step takes a while, be patient)

2- After step 1, you have two folders. Sc0 and Image0. Move all the files from Sc0 into Image0\sce_sys
3- Delete Sc0 (which should be empty after step 2)
4- Rename Image0 folder to CUSA_ID of the game (e.g. CUSA09171)
5- Find all the files with *.prx, *.sprx extentions. Take a note of their path for later.
Example:
CUSA09171\sce_sys\about\right.sprx
CUSA09171\sce_module\libc.prx
 CUSA09171\sce_module\libSceFios2.prx
6- Copy files found in step 4 AND , CUSA09171\eboot.bin, CUSA09171\sce_sys\param.sfo into a temporary folder
Example: Copy them into BackPort\CUSA09171_temp
7- Drag eboot.bin, and all prx, sprs files (one by one) over UnfSelf.exe file. Each time you do that, you'll get a new file that has -decrypted added to end of the file name. (do not do this step for .sfo file) Example: You should get:  eboot.bin-decrypted, libc.prx-decrypted, libSceFios2.prx-decrypted, right.sprx-decrypted
8- Delete all the original files from BackPort\CUSA09171_temp\ (eboot.bin, libc.prx, libSceFios2.prx, right.sprx) (do not delete param.sfo)
9- Run following command for all the files expect for param.sfo.
downgrade_elf.exe --sdk-version 05.050.001 --verbose "decryptedFile" "DowngradedFile"
Example:
BackPort>downgrade_elf.exe --sdk-version 05.050.001 --verbose CUSA09171_temp\eboot.bin-decrypted CUSA09171_temp\eboot.bin
BackPort>downgrade_elf.exe --sdk-version 05.050.001 --verbose CUSA09171_temp\libc.prx-decrypted CUSA09171_temp\libc.prx
BackPort>downgrade_elf.exe --sdk-version 05.050.001 --verbose CUSA09171_temp\libSceFios2.prx-decrypted CUSA09171_temp\libSceFios2.prx
BackPort>downgrade_elf.exe --sdk-version 05.050.001 --verbose CUSA09171_temp\right.sprx-decrypted CUSA09171_temp\right.sprx

Now you can delete all the files that have -decrypted in their name. We do not need them anymore.

10- Run following
downgrade_sfo.exe --sdk-version 05.050.001 --system-version 05.050.000 --verbose CUSA09171_temp\param.sfo CUSA09171_temp\param_new.sfo
Now, delete param.sfo, and rename param_new.sfo to param.sfo

11- Copy/overwrite all the downgraded files into their respective locations in the original unpacked game folder (In step 5 you were supposed to take a note of the original locations).
Example:
CUSA09171_temp\eboot.bin to CUSA09171\eboot.bin
CUSA09171_temp\libc.prx to USA09171\sce_module\libc.prx
CUSA09171_temp\libSceFios2.prx to CUSA09171\sce_module\libSceFios2.prx
CUSA09171_temp\param.sfo to CUSA09171\sce_sys\param.sfo

12- Open gengp4.exe. Navigate to the location that you have the original game unpacked into (from step 1). open CUSA_ID (from step 4), then click "Generate .GP4 and then click on "Save .GP4". To keep it simple, save the GP4 file in same location as CUSA_ID of the game.
13- Create a directory that you want to save the pkg into it (e.g. CUSA09171_downgraded)
14- Run following command to repack the game.
orbis-pub-cmd.exe img_create --oformat pkg GP4File PATH_TO_SAVE_THE_NEW_PKG
Example:
BackPort>orbis-pub-cmd.exe img_create --oformat pkg "D:\Games\ps4\RESIDENTEVIL_2_Remake\CUSA09171.gp4" D:\Games\ps4\RESIDENTEVIL_2_Remake\CUSA09171_downgraded