In Android, here are the steps for upgrading the firmware.

Step 1.  Go to the Device page. There should be a red triangle indicating a new firmware is available. 

Click on Firmware Version.  Make sure you are connected to the internet before you begin an firmware upgrade.  This is necessary because the new firmware files are located at our servers. 

Step 2. It will prompt you on whether you would like to perform a firmware upgrade.  Click upgrade now to perform the upgrade.

Step 3.  The download process will commence.  

Step 4 Once it finished download, it will start the install and show a percentage progress.  The background screen will revert to an disconnected stage.  The percentage of progress will be shown in the grey box.

Step 5 Once completed, the Marlin will reconnect and the updated Firmware will be shown. 

Step 6. Please perform the calibration of the device again.  For details of how to perform the calibration please refer to the FAQ.

It is also recommended to clear the Flash Memory at this time.  Just click on Storage Occupied and select "Yes"