How to Download and Install MIUI 9 on your Xiaomi Smartphone
Steps for Installation
Step 2. Now users have to connect their smartphones with USB to PC, click on the refresh button in the Flash Tool APP and it should show device ID. If it will not show, then all you have to do is install Mi PC Suite and drivers from here. Now, extract the fastboot ROM downloaded, to a folder on PC.
Note: Users should remember one thing that you should not remove your device while it is flashing.