WARNING: You REALLY need to UNDERSTAND and read EVERYTHING or you MAY brick your phone!
Purpose of this thread:
To get you, the locked or unlocked (bahahaha, sorry) Droid Turbo XT1254 owner, from any version to 4.4.4 (KDF21.128-15.15).
Things you will need:
Use the RSD Flasher with KEEP DATA to flash this to your phone with RSD.
Use the House of Moto with KEEP DATA to flash this to your phone with fastboot.