Disclaimer: Modifying your Nintendo Switch violates its warranty and may result in a ban from online services (Nintendo Online). This post is for educational purposes only. Always check your local laws before attempting hardware modifications.
You are using an outdated version of Lockpick, or your tsec firmware files are missing from the SD root. Fix: Download the latest Lockpick_RCM.bin . The newer versions bundle the necessary firmware internally. Alternatively, place the sept folder from Atmosphere onto your SD card. lockpick rcm.bin
If you own an unpatched Nintendo Switch and want full control over your hardware, lockpick_rcm.bin is the first step down that rabbit hole. It is safe, open-source, and has been vetted by thousands of users. lockpick rcm.bin