A "3.55 fix" for Dead Space 3 typically refers to a modified game file (or "EBOOT") created for PlayStation 3 consoles running Custom Firmware (CFW) version 3.55.
If you are looking at archival threads or trying to get this specific setup working on legacy hardware, the community relied on a few primary methods: Fix dead space 3 3.55
EBOOT and SDAT Replacements: Scene groups released specific .pkg files and modified SDAT files customized for the game's regional codes (like BLES01705 or BLUS30629) to bypass the checks and fix the saving mechanics. Start Dead Space 3 and go to the game's options menu