Had an older UPS that finally died...battery no longer holds a charge. Bought a new APC Back-UPS ES 750.
With nothing plugged into it, I plug it into an outlet. When I press the on button, it blinks green 16 times and then emits a constant tone.
I called tech support and was told that it might not yet be charged. I have had it plugged in almost 10 hours. I get the same result now.
I have tried it in different outlets...same result. If I hold the power button in to force a self test, a little red light with an X on it lights up. Any help would be greatly appreciated.