You'll need Ubuntu 16.04 and these tools installed:
sudo add-apt-repository ppa:ubuntu-sdk-team/ppa
sudo apt-get update
sudo apt-get install ubuntu-device-flash
sudo apt-get install phablet-tools
Use magic-device-tool for installing CyanogenMod 13.
This proccess will install you:
- TWRP as boot loader manager, this is the key for next steps.
- CyanogenMod 13.
Copy that .zip file to the phone (if you need space, first wide it).
Restart in recovery mode (power on + volume up).
Choose in TWRP > Install, choose the .zip file.
Reboot and it's done!
If you want Google Apps, go to the Meizu Store and choose Google Installer and then install Google Play and everything from there (Don't uninstall Google Installer app because you'll not receive more messages from apps like Telegram).
If you want to return to Ubuntu Phone, you can use the magic-device-tool app again.