I just bought a 2014 GTX 155 with 60 hours. Looks like new. It ran perfectly for the 1st tank. I went away for a week and now it won't wake up when you press the red button. Display is blank and no sound. Battery is charged and all fuses are whole... Even tried waking it up with the charger attached in case the battery was weak. 14 V. What could it be?