We have heard from several customers that have issues with DC40 collars that won't turn on.  Unfortunately, these collars are no longer repairable through Garmin's repair program. A couple things you can check before calling would be to see if the Red light turns on, or if the Blue light turns on when you connect it to a charger.   If you cannot get either light to turn on, it is not considered to be repairable. For more information about contacting Garmin Warranty or Repair department please visit their Website at www.garmin.com or call their support number: 1-800-800-1020 Here is a Short Video showing the problem with a DC40 collar.