There are three ways HTC update:
- Using recovery (to update installed OS)
- Using RUU Firmware (to recover HTC with Qualcomm SOC)
- Using SP Flash Tool (to recover HTC with MTK SOC)
If you want to install the HTC update using recovery – download the official update, reboot your phone or tablet into recovery mode and click “Install update from SD card”.
To install HTC update with RUU firmware – download and install drivers and ADB&Fastboot, download official firmware and flash it by instruction.