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:
Sites like Restore.Media or Online Converter specialize in fixing M4A files that were cut off (e.g., phone died during recording). RecordTMP (32) m4a
Many third-party voice memo or call recording apps use this naming convention for active recordings. If the file won't play, it is likely
If the file doesn't have a proper dot before "m4a," try renaming it to RecordTMP (32).m4a to see if your computer recognizes it. If the file won't play