The whole process of flashing the TWRP recovery can be divided into two main steps:

Unlocking the bootloader
Installing the custom recovery (which here is TWRP)
Downloads needed for the process:

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AdbDriverInstaller
Adb+key
Terminal_1.0.70
BusyBox
ADB
Unlock_bootloader.sh + twrp_2.8.7.0.img
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Try to follow the steps to the ‘T’ as any wrong move could mean replacement of the motherboard. Also, before you start, you should root your Meizu M2 (steps of which you can found online or you can contact me).

Things to remember:

You should be on the Flyme OS 4.5.4I and not on the Flyme 5.
Enable the USB debugging while your device is connected to the PC.
Your device should be rooted with SuperSU present.
Once you are all done with downloading the things needed, lets start with the process:



Download and install the AdbDriverInstaller and the Adb + key on your PC and laptop along with the drivers for your Meizu M2.
Download the Busy Box and install it with root permission.
Download and install the Terminal app with root permission.
Copy the “unlock bootloader.sh” to the root directory of the device.
Run the Terminal app.
Type “su” and allow the root privileges.
Further type “sh /sdcard/unlock_bootloader.sh”
Unpack the files present inside the “ADB” folder in the C: drive.
Hold “Shift” and right-click on the folder while you select the option of “Open Command Window”
Once you do, you will see the command window open with the directory you placed the “ADB” folder at.
Type “adb reboot bootloader”. Doing so will lead to rebooting of your device in the bootloader.
Once you are at the black screen with tiny text on the buttom saying: Fastboot Mode
Type “fastboot oem unlock” in the command window.
A message about voiding your warranty will come, press “Volume up” to continue.
Wait for the bootloader to get unlocked. And once it is done, turn off your device.
Power up the phone and boot into the OS.
Check if the device is working OK.
Now type “adb reboot bootloader” again to enter bootloader again.
Then type “fastboot flash recovery twrp_2.8.7.0.img”
Wait until the process is over.
Again turn off the device once you are done.
Power on the device and check again if it boots, if it does then boot into the TWRP recovery to check if that is installed right.
Power off the device and hold the”Volume Up and Power button”.
And if everything went right, you should boot into the TWRP recovery 2.8.7.0. So, now you can use this to flash international ROMs of Flyme or any other custom ROM you like.