Downgrading a PS4 from firmware 9.60 to 9.00 is generally not possible
Even if 9.00 was your previous version, reverting is an extremely difficult hardware modification. It is not a software "hack." Soldering skills : You must solder wires to the chips on the PS4 motherboard. Specialized tools : You need a hardware flasher like a Teensy 4.0 how to downgrade ps4 9.60 to 9.00