If you are not sure about your Gemini version, just check under Settings -> Wireless & networks. If you see a menu called SIM cards, then you have an x27 Gemini, otherwise you have an x25 Gemini.
After selecting the partition size, you can select the operating systems to use for each boot mode. Gemini supports 4 boot modes(see the Linux boot notes section below for more information):
* Boot 1: This is the default booting option when no buttons are pressed.
==Flashing the Gemini with an alternative Linux firmware==<div style='margin: 0.4em 0px 0.5em; color: #252525; font-family: 'Source Sans Pro', sans-serif; font-size: 15.008px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;'>Be sure to follow the previous step to store a copy of the NVRAM partition as backup. Now, run the Flash tool software and click back on the the '''Download''' tab tab. Next, locate the '''Scatter-loading File''' option and click on the associated '''choose''' '''button''', as highlighted in the picture below:</div>
[[File<div style='margin:flash10.png|center|640x419px|border]]4em 0px 0.5em; color: #252525; font-family: 'Source Sans Pro', sans-serif; font-size: 15.008px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;'>Select the '''Firmware Upgrade''' option from the drop down menu. This will automatically select all the partitions in the table.</div><span style="color: #252525; font-family: 'Source Sans Pro', sans-serif; font-size: 15.008px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;">To start the flashing process, just click the big </span><strong style="color: #252525; font-family: 'Source Sans Pro', sans-serif; font-size: 15.008px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial;">Download</strong><span style="color: #252525; font-family: 'Source Sans Pro', sans-serif; font-size: 15.008px; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: #ffffff; text-decoration-style: initial; text-decoration-color: initial; display: inline !important; float: none;"> button, connect your Gemini to your PC and restart the Gemini. Once booting, the flash tool will detect the unit and will start flashing the device with the selected firmware.</span>
Now, open the firmware folder from the firmware zip file you downloaded and select the scatter file. If you selected an Android firmware, then the scatter file will be called''' Gemini_Android.txt'''. If you selected an Android==<br /><br />Linux firmware, then the scatter file name will depend on the space you reserved for them, for example''' Gemini_x27_A26GB_L30GB_Multi_Boot.txt'''boot notes==The multi boot mechanism works as follow.
Starting from a switched OFF Gemini, press the Esc (On) key to start the unit until the Gemini vibrates. Once you select feel the scatter file, vibration you can choose the boot mode by pressing the table should be populated as belowfollowing key combination:
*
* Boot 1: This is the default booting option when no buttons are pressed.
* Recovery Mode: Esc (On) is pressed. This will always boot into overy mode.
* Boot 2: Side button is pressed.
* Boot 3: Esc(On) key is pressed and Side button is also pressed
[[File:flash2.png]]
Make sure all the partitions are found and are checked. If some partitions are not found (location tab is empty), double checked that you unzipped the Linux module in the firmware folder.
Finally, change the '''Download Only''' drop down menu to '''Firmware Upgrade''' and click on the '''Download''' button. When switching between a standard Android to a dual boot Android/Linux firmware, you must use the '''Firmware Upgrade '''mode because you need to format the device and change the partitions.
Connect your Gemini and restart it. As soon as the Gemini is rebooted, the flash tool will detect the device and it will update the OS with the selected firmware.
==Manually Update Android firmware==
Planet Computers provides over-the-air update for standard Android installations. For custom installation, you will need to manually update the Android firmware.
To update the Android firmware, simply download the latest Android firmware from [http://support.planetcom.co.uk/index.php/Gemini_Firmware http://support.planetcom.co.uk/index.php/Gemini_Firmware] and use the '''Download Only''' option while selecting only the system partition, as in the screenshot below
[[File:Screen_Shot_2018-06-20_at_15.57.55.png|center|640x421px|border]]
After the screen turns ON you can release the keys.
==Linux dual boot notes==
The dual boot mechanism works as follow:
* '''Dual boot Android-Linux firmware'''
