These chips worked by intercepting the communication between the Switch’s processor and its storage/memory. They contained their own processor (often an FPGA or a cloned microcontroller) that would "glitch" the boot process, forcing the Switch to load a custom payload from the chip's memory instead of the official Nintendo OS.
The software side was also fortified. The Switch operating system (Horizon) was updated to version 9.0.0, which introduced stringent checks. Even if you managed to boot a CFW, the system would constantly check the validity of system files. If it detected a mismatch, it would instantly panic and shut down.
For years, the Nintendo Switch modding scene has been divided by a clear line in the sand: the "unpatched" launch units (2017–early 2018) versus everything that came after.