I am a first-time G-Shock owner/user. I just received a used G-Shock G-2310 which I bought online. It is functioning perfectly except for the backlight. When I press the backlight button, the display blanks out for a couple of seconds then comes back. The entire display (EL - electroluminescent) which is supposed to "glow" didn't. The power is at the highest Level 1 and all functions are enabled. I am not experiencing rapid loss of power. I even tried leaving the watch for 4 hours on the window pane (indirect morning sunlight) to no avail. Please help. Thank you.