WE HAVE BOUGHT A SECOND HAND TREADMILL. IT WAS SHOWN WORKING AND WE HAD TO DISMANTLE THE ARMS FOR TRANSPORTATION. WHEN WE GOT THE TREADMILL HOME WE RE-ASSEMBLED IT BUT WHEN IT WAS PLUGGED IN ALTHOUGH THE LIGHT BY THE PLUG IS ON THE SCREEN IS BLANK AND THE TREADMILL WILL NOT START. ANY SUGGESTIONS PLEASE???