Device: Nintendo New 3DS LL (Japan)
System Version Before Process: 11.17.0-50J (Japanese version)
System Version After Process: 11.5.0-38U (US version)
Firmware Issue: The region and firmware version changed unexpectedly, and the new version is outdated.

Guide Link Used: https://3ds.hacks.guide/installing-boot9strap-(mset9-cli).html

Steps to Reproduce:

1. I followed the instructions to install Boot9Strap on New 3DS LL.
2. I followed each step carefully and did not encounter any errors during the process.
3. After completing the installation, the New 3DS LL rebooted, but it displayed a different system version 11.5.0-38U rather than the original 11.17.0-50J.
4. The region was also switched to “US,” and I lost access to the original Japanese firmware.
5. Additionally, I now have two “System Settings” icons on the HOME Menu, which appear to be duplicates.