Edited by Tymcio at 2016-11-29 14:01

I have read about many people complaining that their screen turned upside down after updating firmware so these are the steps to fix it without visiting the service center. These steps have been shared with me by 路好远 and i am very grateful for that.
First of all root your phone. For that go to Settings>Fingerprint & Security>Root Permission>Accept the Agreement>Ok>Enter your Flyme account password (If you don't have a Flyme account then please create one.)

After rooting download any root explorer, grant root permission and go to the root of your device.

After going to root go to the system folder open the build.prop file. (Note that there will be two folders namely sys and system please select system)

Use any text editor and not text viewer that can make changes to the file.

After opening the build,prop file search for ro.sf.hwrotation=180.

Change it to ro.sf.hwrotation=0

Save the changes and restart your device and done!!

There are some caveats though:- The recovery will still be upside down(as of now there is no solution to this)  and the occasional display flickering when you restart your device. To solve this just restart the device again and it will stop flickering.

Before following this tutorial i suggest you to turn on visual feedback for touches as your screen is upside down you will find it difficult to use the phone. If you turn this on atleast you'll have a better idea of where you're clicking.

To do this go to Settings>Accesibility>Developer Options>Show Touches.

Thanks for reading! Do comment if you found this useful.