Earlier today, HTC released the One M9 Nougat update for carrier-free unlocked sets around the world. The update is being pushed out gradually to all such One M9 sets the world over, but if you don’t like waiting for it too much, then you can download the OTA file of the update from below and upgrade to Android 7.0 and Sense 8 yourself right away.
First things first, though, for this to happen successfully, you must be on software version 3.35.617.31 right now, as this is the base version for the update. Also, in case you are on 3.35.617.21, not on .31, then you can use this OTA file (size: 91.17MB) to update from .21 to .31, on which Nougat OTA would work. Install the OTA file the same way as provided below for the Nougat OTA version 4.14.617.6.
Backup important files stored on your device before proceeding with the steps below, so that in case something goes wrong you’ll have the backup of all your important files.
How to Update Manually HTC One M9 to Official Nougat 7.0 +Sense 8
Transfer the OTA file to your One M9. Don’t put it inside any subfolder of your M9.
Reboot your One M9 to recovery mode to access stock 3e recovery.
Choose Install update from phone storage. And select the OTA file you transferred in step 2 above.
Let the update install. Wait till then. When done, you will be back on recovery home screen. Select the ‘reboot system now’ button to restart the device. And be ready to greet Android Nougat on your HTC One M9 with Sense 8 a top it.