Hardware like the Teensy or TC++ 2.0 is required to dump and patch the console's internal chips. The Downgrade Process (Overview)
The version that was installed before your last update. ps4 tool downgrade v100 new
How to Revert the PS4 to a Previous Firmware (Full Tutorial) Hardware like the Teensy or TC++ 2
A free, open-source tool by developer Andy-man for managing NOR and Syscon backups. ps4 tool downgrade v100 new