hai dear friends,
       flyme team they released public beta firmware with nought in chines version, so many people confusions with this firmware,
1. how to install this
2. this have bugs?
3. is this brick my device?
4. can i come back to 5.1 form 7.0?
yes your two confusion is true this firmware have bugs, and you cannot come back to lower versions i mean 7.0 to 5.1. ok, then this firmware is only for m681h not suitable for (L) version devices.
this firmware is installation is little different,
that's nothing let's see,
NOTE:- BACKUP YOR VALUABLE DATAS BEFORE INSTALL THIS AND I AM NOT RESPONSIBLE FOR ANY DAMAGE OF YOUR DEVICES THIS IS JUST FOR EDUCATING PEOPLE
1. download m3 note latest Chinese bata put in internal storage and copy that update file in to your  pc's desktop( I'll ask you later why)
2. touch update file it will show you system update pop message as normal.
3. must do not give clear data with update
4. do not press power botton on installation process please wait because it will take 15minuts
5. then it will show you some Chinese options ( wait do not angry and throw your mobile) just nothing that is our meizu stock recovery mode.
6. now you connect device with yor pc with that Chinese mode then open mycomputer there mounted you're mobile as recovery just copy that update. zip file.
7. finish that copy process disconnec mobile
8. see that in display thare first option selected default then second is clear data so you no needed to select
9. then come to last thare two options left and right you touch right one.
10.then device will repeat installation process form beginning it will take 10 minutes
11. then you do factory restore for application not response error, charge issue
12. if consume more battery power? go to security app then go battery then chose low power mode then no need to select turn off network when stand by then chose enable.

enjoy flyme nought beta experience.

NOTE:- this firmware is not stable use this at your own risks

dear friends sorry for my poor English, i know you get angry and your eye getting burning level because of  my English knowledge, i am so sorry for that once again. why you can't try cooling glass Will reading..