The only way to take a modern PS4 on a high firmware (such as version 11.00 or higher) and bring it down to a highly desirable jailbreak firmware (like version 9.00) without a pre-existing Syscon backup is to physically swap the core components of the motherboard.
If you manually soldered a flasher to your PS4 months ago while it was on firmware 9.00, took a complete cryptographic dump of your Syscon and NOR flash, and saved those files on your computer, you can downgrade. ps4 tool downgrade v1.00
To safely navigate the console modification ecosystem, it is critical to separate verified engineering breakthroughs from deceptive software trends. This guide provides an objective look at how PS4 firmware reversion works, the technical barriers involved, and how to spot malicious files. The Technical Reality of PS4 Downgrading The only way to take a modern PS4