Required Files -
MINIMAL ADB & FASTBOOT : https://www.androidfilehost.com/?fid=...ROM ( use latest version ): https://www.androidfilehost.com/?w=fi...
GAPPS ( use latest version ) :https://www.androidfilehost.com/?w=fi...
GAPPS LINK 2 : https://www.androidfilehost.com/?w=fi...
TWRP ( use latest version ) : https://www.androidfilehost.com/?w=fi...
ORIGINAL THREAD : http://en.miui.com/thread-193630-1-1....
Steps --
1. Download the required files from links above.
2. Copy the downloaded ROM and GAPPS file to your phones internal storage.
3. Install "MINIMAL ADB & FASTBOOT" to your computer.
4. Copy the TWRP img file to the install directory of MINIMAL ADB & FASTBOOT, which is "C:\Program Files (x86)\Minimal ADB and Fastboot" and rename it to "recovery.img".
5. Turn off your phone and after its off completely hold the VOLUME DOWN + POWER button to go in fastboot mode.
6. Now connect your phone to the computer using data cable.
7. Now on your computer in "C:\Program Files (x86)\Minimal ADB and Fastboot" folder, hold shit + right click and click on 'Open command window here'. A command window will popup.
8. Now here type 'fastboot devices' and hit enter to see if device is connected or not.
Something like this will be shown - "512e74f5 fastboot" that means your device is connected.
9. Now type "fastboot flash recovery recovery.img" and press enter. It will successfully flash the recovery file to your phone.
10. Now type "fastboot reboot" and hit enter to reboot your device. Once its on turn it back off and this we will boot in recovery mode.
11. After your phone is off, to boot in recovery mode hold VOLUME UP + VOLUME DOWN + POWER button to boot in recovery mode. Now your phone will boot in TWRP recovery mode.
12. On first screen slide to accept the permissions.
13. Backup if u want.
14. Now come back and click on wipe and choose advanced wipe and select all the options except internal storage and micro sd. Now Swipe to wipe.
15. After that's done press the home button and Click on Install and select ROM file and GAPPS file file by clicking on Add more zips.
16. Now go ahead and Swipe to confirm flash. This will take some time so be patience. When its successfully done, click on Wipe cache/dalvik. And then click on Reboot system.
Now you have successfully Installed Android 6.0.1 MarshMallow on your Redmi phone.