This can sometimes bypass a corrupted header and pull the actual audio out.
VLC Media Player can often play "broken" or unfinalized files that other players can't. Import as "Raw Data" in Audacity: Download Audacity . Go to File > Import > Raw Data . RecordTMP (32) m4a
If the file won't play, it is likely missing its "header" (the data that tells a player how long the audio is). You can try these methods: This can sometimes bypass a corrupted header and
How to Recover Corrupted Audio Files