M3 autoshutdown

I have some troubles with M3 when I tried to burn-in Earphone with it. It always auto-shutdown after play several songs hence, so that I can't leave it alone to burn-in. Sometime my M3 stop continuing to play next song when the previous one has ended. I don't know whether it's because of firmware problem or music files.

Any suggest?

You have to choose "repeat - all" in the music menu, otherwise it will stop after playing the last song of the selected folder. This can happen very fast if you have activated "random" play.

Unfortunately, I have chosen "repeat-all" for all the time and I have chosen "sleep timer-off" also.
And it still happen even after I've upgraded firmware to M3 T2.004.6 again.

Then it might be because of some of your music files - as we all know the M6 and M3 have problems with the interpretation of the ending of some songs, resulting in stutter, harsh sound, long pause or stopping.
If you want to burn in your earphones, you could use only one song/playlist or radio to play nonstop.