==>Once you’ve downloaded the Android M zip file, Rename it to update.zip
==>Place it on the root of your SD Card (it shouldn't be in any folder)
==>Power off your phone
==>Hold Volume Up + Power Button
==>Release power button and tap volume up once you see the "Infinix" Logo
==>It will show you a dead Android robot with a red sign
==>Press Volume Up or Volume down (device dependent) to get into the stock recovery
==>Scroll down with Volume button to "Apply Update from SD Card"
==>Scroll down to the update.zip and select with the Power Button.
Install, and once installation is done, reboot your system and wait for system to start.