APC Smart-UPS 1400 no power

I have an APC Smart-UPS 1400 (model SU1400BX120) that has no indication of power whatsoever. When plugged into a known-good AC source, there are no indicator lights, audible tones, and no response to the power/test switch. The battery measures at a whopping 0.33 VDC, and the rear-mounted "Overload Protector" currently measures as a short (un-tripped), with continuity confirmed from both blades of the power cord to the circuit board (and ground to the equipment case). No other visible fuses were seen on the circuit board, or elsewhere in the case. All other cable connections have been checked & verified.

Age and past history of this unit are unknown, as I am recently filling a one-deep position, with no notes whatsoever left by my predecessor as to the state or condition of numerous pieces of equipment left laying around.

Before I give this thing the heave-ho, other than replacing the most-likely spent batteries, is there anything else that would/could be causing a complete "no power" indication that I can check?