If the battery reaches the critically low level, your Mavic will auto land at its current location
(it will never RTH). While you can move the throttle stick to the full up position to prevent the Mavic from descending and/or help move your Mavic to a better landing location, there is no way to cancel the auto landing.
Low Battery RTH is a different scenario. When the Mavic detects it only has enough power to make it back to the home point, Low Battery RTH will be initiated and a message will be displayed on the screen in DJI GO to alert you that your Mavic is going to auto RTH in 10 seconds. If you do not cancel that procedure from the screen in DJI GO, your Mavic will start returning home after 10 seconds. After your Mavic starts returning home, you can cancel that process by either pressing the RTH button on your remote controller or by canceling it from the left side of DJI GO.
If you'd like to prevent this from happening altogether, you should disable the "Smart Return-to-Home" setting in DJI GO.
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