HTC has officially published One M9 Dev Edition’s RUU package for the Android 5.1 (2.8.617.4) update it rolled out over the air a week ago. You can download this RUU executable below.
Download One M9 Dev Edition 2.8.617.4 Android 5.1 OTA Zip
HTC has officially released the Android 5.1 Lollipop update, version 2.6.651.11, for the One M9 (Developer Edition) through OTA. This 800 MB is aimed at fixing issues related to heat management, connection stability, camera quality and battery life. You can download this OTA package via the direct download links provided below.