Use if you have an official update.zip package and can access recovery.
What you need:
: Manual upgrades typically require downloading the firmware to a computer and connecting your DOOGEE U9 via a wired connection using a "brush tool". Pre-Update Tips How To Update Software On DOOGEE U9
A: No. Rooting the device usually breaks the OTA update mechanism. If you have rooted your U9, you will likely need to manually flash the stock firmware to update it. Use if you have an official update