Firmware in Recovery:
Copy to the root of the memory card zip-file with the firmware, not Unpack it. The file name must contain only numbers and letters, spaces and special characters are not allowed.
Turn off the smartphone, hold down the volume up button and the power button until the boot logo.
In recovery select "install zip from ..." and the need to file with the firmware.
After the installation is complete select "reboot system now" (to reboot the device.) Depending on the version of recovery menu navigation can be done in different ways. Usually the volume button thumb points, and the power button or menu confirm the selection.