By using advanced hardware tools (like a Teensy or Raspberry Pi Pico) and performing micro-soldering on the console's Syscon and NOR chips, technicians can trick the console into switching back to the previous firmware slot.
Hardware downgrade is not a “downgrade” in the software sense — it’s component replacement. It is not viable for typical home users. ps4 downgrade 13.02 to 9.00
Furthermore, the update process itself is cryptographically sealed. Sony signs every official firmware update file (PUP) with a private key. The PS4’s boot ROM contains the corresponding public key and will only install a firmware that is cryptographically verified and, crucially, in version number than the current one. This is known as an anti-rollback mechanism. Even if a user managed to bypass the efuse check, the bootloader would reject the older, 9.00 update because its security version counter is lower. Any third-party tool claiming to “factory reset” or “force flash” an older firmware is simply lying; the signature check is baked into the read-only memory of the console. By using advanced hardware tools (like a Teensy
From the PS4’s inception, Sony implemented a hardware-based fuse or anti-rollback system. Inside the console’s Southbridge chip and the main system-on-a-chip (SoC), there exists a set of one-time programmable fuses. Each official firmware update updates certain keys and increments an internal fuse counter. When the system boots, it compares the currently installed firmware’s version number against the fuse count. If the firmware version is lower than what the fuses indicate, the console refuses to boot, effectively bricking itself. This is known as an anti-rollback mechanism
Firmware 9.00 is the last highly stable jailbreakable firmware. Firmware 13.02 patches all known public entry points, including the BD-JB (Blu-ray Java) used on 9.00 and the PPPwn RCE used up to ~11.00.