It's still trying to play a song, according to the serial output. You need to do this, as was mentioned earlier in the thread, to stop it from playing a song.

Then, you need to continue with the remainder of the instructions here so that the database can be rebuilt.

Once you've done that, do not play a song or a playlist. Boot the player and tell us whether or not it continues its previous behavior of locking up after it's been on a few seconds.

If it continues to lock up, even if it's not playing any songs, then I would consider it highly likely that it's a hardware problem.