Xiaomi Mijia 4K Action Camera updated its firmware with the English menus! The followings are how to update the firmware.
Download the firmware and put it into the root directory of an empty high-speed memory card.
Make sure the camera’s battery is full. Turn off the camera and insert the memory card into the camera.
Turn on the camera, there will be a Chinese prompt on screen. Touch the right button to confirm the firmware update.
The camera will power off and flash its lights for 1-2mins. Once the camera finishes updating the firmware, the camera will reset.
After the camera reset, swipe down from the screen’s top.
Press the settings button.
Scroll all the way to the bottom of the settings menu.
The language selection is the third option from the bottom of the list.
Now, your Xiaomi Mijia 4K Action camera is English! Enjoy it!