How to make firmware upgrade

Instructions

download the firmware file (zip file)
unpack the .zip file to get a file with .bin extension
connect your voice recorder with PC and copy the firmware file (with BIN extension) to the root folder of internal memory of voice recorder.
disconnect the voice recorder using the function of Safely remove hardware (click the icon in the Windows taskbar)
power on your voice recorder and check if batteries are fully charged
open menu and choose Settings, more, firmware upgrade and click Confirm. After that wait for the beep informing about finish of operation. How to do it without a need to understand the voice guide? Press and hold right bottom button, press up button (middle top), play button (central), up button again, central button again. Repeat pressing up and central buttons the same way until the voice recorder starts the firmware upgrade process. Now, wait a few minutes until it finishes.
open menu and choose Settings, more, Default settings and click Confirm.