What I've found on other boards, and by experience, is that if the recording stops because of a crash or battery failure the video file is not properly "closed". Without removing the sdcard, put in a good battery and reapply power to the bird (no need for remotes or phones/tablets). Wait a few seconds, and then turn off. Remove the sdcard and check it in a computer/tablet/phone...the latest file should be good to go now.
Reapplying power to the camera allows it to "close" the file.
I have even removed the sdcard, checked it on the computer, yes the last file was corrupt...I reinserted the card into the bird and powered it on...then powered on the remotes and my phone...checked the album in DJI app after everything was connected and the file was "restored"...
No guarantee, but it has worked for me a few times. I doubt that this procedure will work on a truly "corrupted" video file...
Good Luck.