@Ramtin: There is no user center apps on flyme 5.1.6G at meizu m2.. That apps only available on meizu m2 note.. I have tried to install the user center apps v5.7.0 from meizu m2 note to m2, the installation is success & I can login to my flyme account, but the Security - Root Permission still doesn't exist.. Btw, I can't download the link given above..  May be lack of forum authority.. Could you please upload to Dropbox or other? Thanks much in advance..

@Ramtin,  Update: now I can download the file.. I will give it a try then tell u the progress.. Thanks.

Re-install rom means you talking about software or something else.  Please tell how to re-install rom and please help about unbind my number from flyme account

I'm still getting error accessing server.

Now i got it. Here's what i did.
I downloaded the MzAccount.apk given by Ramtin, then installed it to replace the user account, i did not reboot yet instead i go to Settings>Security and Root Permission, check the agreement and enter password and "BAM", the phone rebooted after. That means you're rooted.

Thank you Ramtin.

Don't write tutorial without knowing problem. The main problem is that flyme account can not be signed in with flyme os5.1.6.0

@Ramtin: The file UserCenter_5.0.6.apk is identified as an Agen-LDV Potential Unwanted Programs by Avast.. Are u sure that it's secure?

I mean place update.zip (flyme 5.1.6 update.zip file that you download from this site) in your memory and upgrade your device again (without wipe data, do not tick wipe data) . After placing your update.zip you can go to flyme "file manager" app and click on zip file then seleck your update.zip and "upgrade now"

First of all many people root their 5.1.6.0 devices with my tutorial please, see the topic pages before post false negative comments. Secondly, "Error accessing server" when you wanted to root your device in 5.1.6.0 was not related to meizu servers or our meizu accounts. There was was some mistakes with user center app codes that in app I posted here they're corrected and works. You can easily root your device with my tutorial. If you have problem with sign in to your account it's not related to my tutorial or flyme 5.1.0.6. Maybe there is some problem with your own phone or account. Maybe your password is wrong or your ISP block you to connecting to meizu servers or you have internet problem etc... but, it was not issue with flyme 5.1.6.0.