Download Stock Firmware for your Lenovo VIBE Z Smartphone directly from official Lenovo servers. You can use this Stock ROM to flash or unbrick your Lenovo Z Smartphone. Or you can unroot your device using this Stock ROM for Lenovo Z smartphone.
Download and put this Lenovo Z Stock ROM zip file at the root of your SD card. And then go to Recovery menu and apply updates from SD card. Click here for tutorial.
File name: VIBEUI_V2.0_1516_7.421.1_ST_K910_WC4A.zip
File size: 751 MB