To keep it as light as possible DJI did not install any fan on the mini 3 pro.
As a result when the propellers are not rotating to cool the drone, it can become quite hot which is not good for the electronics.

Here is a stand including a 4010 5V USB fan which will blow some fresh air inside the bird throught the bottom battery holes.

It is enough to prevent overheating when installing a new firmware or downloading some files.

I tested it in room at 20°C, during 15 minutes, the temperature of the battery reached 32°C with the cooling stand, while without it can quickly go above 40°C...

The air intake is located at the bottom of the stand, please place it on a table or a flat rigid surface...

The stand can be secured to the mini with a rubber band going around the drone and attached on two legs of the stand, but this is not mandatory...