Download Android OS 5.1 stock firmware for MyGica ATV495PRO TV Box from here.
Image file size: 597.9 MB
Platform: Amlogic: S905
Source Build Sample: Free app builder
Caution: Please do not update firmware unless you know what you are doing, you really want it or it is absolutely necessary. Firmware updates may occasionally have bad results, like bricking your device, temporarily or permanently. The firmware update process is done entirely at your own risk. Before attempting to update the firmware, back up your data