From Planet Computers
If you have trouble updting your Gemini using the over-the-air udpate mechanism you can follow the guide below to perform a manual update.
To proceed, start by downloading the update archive from http://support.planetcom.co.uk/download/Android8_4G/
udpate.zip. It's easier to download this archive directly from your Gemini, just open a browser and point it to the URL above. The file will be downloaded in your Download folder.
You can also download the file on a computer and copy it to your Gemini Download folder in a second stage.
Once the download is completed