For compatible consoles, the procedure begins with a software exploit. In the current landscape, the "PS3 Toolset" by bguerville is the industry standard. Users must navigate to the toolset via the PS3’s built-in web browser. This toolset leverages a memory exploit to patch the CoreOS, essentially "tricking" the system into accepting an older or modified firmware version. Before proceeding, it is mandatory to perform a Flash Memory dump. This backup is the only safety net available if the system bricks during the write process.
Before attempting any downgrade, you must identify if your console is physically capable of running older firmware. how to downgrade ps3 firmware 4.89 to 4.88