1.Enable the USB debugging mode on your HTC Butterfly X920D Smartphone.
2.To perform this procedure you need to installed the TWRP Recovery on your phone. So, if you not yet installed then do that instantly and then continue this procedure.
3.Finally, make sure the charge of your device is full or atleast 75%.
Procedure to root HTC Butterfly X920D Smartphone:
1.First download the su_buzybox.zip.
2.Next connect your HTC Butterfly X920D Smartphone to the computer and copy the downloaded zip file to your SD card.
3.After that boot your phone into TWRP recovery. To do that, you need to press the Volume Down and Power button simultaneously until you presented with the fastboot menu, after that use the Volume Up/Down buttons to go to recovery and then use the Power button to select it.
4.Once you are in TWRP Recovery, tap on install, navigate to the location of downloaded zip file and select it.
5.Next confirm the installation to begin the flashing process.
6.Once the flashing process is finished, reboot your phone.
That’s it! Now, your HTC Butterfly X920D Smartphone was successfully rooted. To confirm the same open the app drawer, you will see the Superuser app.