Every time I tried to update my Mavic Pro, it could never complete it! It would always over heat and shut down! But now I use one of those USB Cooling Fans and it kept it cool enough to update!
Where are you attempting to update the firmware? The aircraft shouldn't be overheating if you're in a normal temperature controlled environment (around 72°F).
It doesn’t overheat when it flies, only when I update software or when using the Virtual Flying program within the App! I suspected that the internal Cooling Fan was not running, but it was! Go figure!