Below is a complete, ready-to-publish blog post sharing how to update the firmware on the HTC One X9. How to Update the Firmware on Your HTC One X9
Because this is a firmware-level change (affecting modem, secure enclave, and power management ICs), the installation will take slightly longer than a typical OTA — approximately 4–6 minutes. A single automatic reboot will occur. Firmware Change Update on HTC One X9