Have you dried deleting the song? Go to file manager, then press Music. This willbring up all the files, find the song and either delete it or move it to another location (a computer or a cloud hosting service like Google Drive or Mega) Make sure it is off that device.
Try opening it, and fill it with rice to completely dry it. After 24 hours, take the rice out and look at a teardown to see if your device is wired improperly. Update 2/2/17: Actually not rice just dry it with a hair dryer but DO NOT microwave as that is dumb and stupid. Update 3/2/17: Apperantly rice isnt the way to go, use Isopho whatever alcohol to clean the inside and remove corrosion.