As part off your regular maintenance you should update the aircraft firmware and then calibrate the batteries.
Here is the official firmware update for your Autel Evo 2 Enterprise.
https://www.autelrobotics.com/download/118.html
Here is a video that explains the process:
1. Download the file, unzip it and copy it to a blank (formatted) SD card.
2. Put it in the drone. Power on the remote, start the app and then power on the drone. (Make sure the drone and the remote are fully charged)
3. Leave the drone and remote on. In a minute or 2 you should see a message on the display indicating a firmware update is in process.
4. Once the update is complete, remove the battery and replace with another battery. Power the unit back on and repeat the process. This will update the remaining batteries. Do this for all of your batteries.
5. Once you have completed updating the drone and batteries you can reboot the system. Enter the menu and look for the sub menu that says about. Look for software updates. Download and update the App for the remote.
*note you have to reformat the card and install the firmware each time you update each battery.
Once complete you can check the firmware table in the app to make sure all of the components are updated.
Here is the firmware table. Compare these versions to all of the components on your drone to make sure they match.
https://www.autelrobotics.com/download/119.html
Now, to calibrate your batteries:
Drain them down to critical, as low as 5% and fully charge them back up. You can do this by leaving it powered on on the workbench. Repeat this for each battery and put this on your maintenance schedule for about every 20 flights. This process resets the internal circuitry to match the battery’s current state.
Since you had an unexpected low power incident, I recommend testing your batteries to make sure this process corrected the problem. Fly close to home and verify that that batteries do not show a low power state unexpectedly.
Finally, how you store your batteries can make a big difference on how long they last. I know public safety agencies like to put them away full so they are ready when you need them but this comes at a price. I usually suggest keeping only 1 battery fully charged and the others stored at 50-60%. If you get a call you can put the others on the charger and by the time you cycle through the first pack you should have another ready to go. Rotate the full pack once a week. You can read about battery care here:
While this article talks about another manufacturer’s battery, the principles are the same.