Step 2: After downloading the Mi flash tool and ADB driver install both of them on your pc. After that restart your pc
Unzip the Rom and unlock bootloader.rar
(here i will use the lollipop based modded bootloader file.
now replace the Recovery.img and emmc_appsboot.mbn
Step 3: Switch off your phone and enter into Fastboot mode by pressing "Volume down + Power button" at the same time.
then connect your device to pc by USB cable.
Step 4: Open Fastboot EDL folder and Run edl.cmd.
Step 5: Launch Mi flash tool when its connected to your device with usb cable. you'll see a figure like i show with your device id.
Step 6: Again enter into Fastboot mode by pressing " Volume down+Power button" at the same time.
Run unlock bootloader.bat.
Step 7: Boot into TWRP mode by pressing "Volume up+ Powerbutton" at the same time directly from EDL mode
Open TWRP and install SU.zip.