You can download the original image from http://www.zgemma.tv/.
But in this short guide, I will be using this image from here: https://www.digitalworldz.co.uk/downloads.php?do=file&id=3008.
- Make sure the box is turned off.
- Download the archive.
- Decompress it and upload it to the root of a freshly formatted FAT32 USB memory stick. So the containing folder will be 'zgemma', straight on the root.
- Insert the USB in the USB port from the back.
- Turn the box on.
- After a few seconds, it will say 'USB' on the front display. Press the Power button on the front panel, notice the display will now show 'Flash'.
- After a few minutes the box will reboot, then you can safely take off the USB memory stick once the box has rebooted.