There are a number of factors that can lead to an update failure when updating the firmware on the DJI Mini 2 SE.

1. The battery level of the aircraft or remote controller is below 20%.

2. The aircraft or the remote controller is powered off during an update. If this happens, restart the aircraft and remote controller, and try again.

3. The network is disconnected during a firmware download.

4. Your smartphone interface is switched to other applications during a firmware download.

Please note that the aircraft will restart multiple times during an update and automatically power off after completing the update.