Lenovo ZUK Z1, runs on Cyanogen OS can now be updated to Android 7.0 Nougat via unofficial CyanogenMod 14 custom ROM. ZUK Z1 will not get official Cyanogen OS 14 (Nougat) anytime soon, however, if you want to experience the new Android Nougat on your phone right now, you can install the unofficial CM14 on it.
CyanogenMod 14 ROM (Android 7.0 Nougat) for Lenovo ZUK Z1 mentioned here is an unofficial build and not yet stable for daily use. It is experimental and might have many bugs that have not been fixed yet. Though most things are working, you may come across issues while using it, so do not install on a regularly using device.
To install CM14 Android 7.0 Nougat, your Lenovo ZUK Z1 should be unlocked, have root access and latest version of TWRP custom recovery installed on it. Do not forget to back up every data on your phone before installing the ROM.
Important: Before you get start we remind you that the below method is for Lenovo ZUK Z1 with Cyanogen OS. Do not try it on ZUK Z1 with ZUK UI.
Disclaimer: This procedure will void your device’s warranty. Follow the instruction at your own risk. We will not be liable if any damage occurs to your device and/or its components. It is recommended for technically talented users only.
2. Transfer both zip files to your phone’s SD card.
3. Reboot your phone into TWRP recovery mode. To do so, switch off the phone, press and hold the Volume Down, Volume Up and Power buttons few seconds.
4. In TWRP recovery, select ‘Wipe’ > Advanced > and clear cache, data and factory reset.
6. Return to main recovery menu, select ‘Wipe’ and clear cache and data.
7. Finally, reboot your ZUK Z1. It will take 10 – 30 seconds for the first boot. Once booted up, set up and Enjoy Android 7.0 Nougat (Source – OrdenKrieger)