****YOU MUST BE UNLOCKED****



I'll try to explain the best way I can on how I did it.



I downloaded the 9.0.4 full zip file



Extracted the 9.0.4 zip



Put my TMobile oneplus in fastboot



Clicked on flash all



*After it finished flashing, the phone booted up but quickly powered down on it's own and it kept doing it.



Inside the 9.0.4 extracted zip you'll see another zip file called "Other_flashall.zip" I then extracted that zip. Put my phone back into fastboot and clicked "flash-all-partitions-fastboot.bat" I let it do it's thing and the phone booted and was ready to go with no signs of any TMobile in the phone



****YOU MUST BE UNLOCKED****