Me or Pixhawk faulty?

Initially achieved successful Pixhawk set up and operation after meeting a steep learning curve.

Success required I begin “from scratch”, including re-flashing firmware for all components (Pixhawk, ESCs). The Pixhawk would initially arm and then spontaneously disarm. I proceeded by clicking through the wizard and then opening the Flight Data tab. Arming and operation of the Pixhawk succeeded. Good throttle/responses. Prior to achieving reproducible success numerous other approaches were attempted.

After first success the Pixhawk operated as anticipated. I reproduced success multiple times after combinations of closing/reloading of MP, powering off/on the Pixhawk with and without USB cable. Radio and telemetry functioned normally. It appeared quick attachment of the top frame plate and propellers were required. Dring this work no manipulation of the connections or components were required.

Failed Pixhawk operation subsequently occurred. I now repeatedly hang at a flashing yellow main light occurring with loud 10 to 12 beep sequences of the Pixhawk (available material indicates this is a low battery alarm). This does not occur when the Pixhawk is booted after attachment to the USB cable.

When I disconnect the USB cable the flashing and beeping begin after approximately fifteen seconds.
I had encountered this activity a couple of times before my initial success. I believed it related to variance within my approach. It appeared to resolve after my re-flashing of firmware and reprogramming of the ESCs.

I also had begun keeping a written log detailing my sequences and precise actions. Therefore, I returned to the path leading to first operational success without the frame top plate or propellers attached. This included re-flashing firmware and re-calibrating/programming of the ESCs. However, no successful operation results.

I consistently arrive at the final wizard (arming) step. Now, however, advancing through the wizard menu and opening the Flight Data tab does not yield arming or operation of the Pixhawk. The earlier phenomena where the final wizard step exhibited transient arming/spontaneous disarming of the Pixhawk no longer occurs.

I am unable to identify alternative approaches. I now consider the possibility I may have (or caused) faulty Pixhawk operation.

Please consider referring me to additional information enabling alternatives to achieving Pixhawk set up and operation.
My copter set up is:
Current stable software and firmware (no old or Beta versions).
A 2013 3DR 2013 Arducopter kit and electronics package (quad power board, power module, 3DR Ubox GPS/compass, 20A Opto ESCs, blue 3DR motors, 3DR supplied propellers and all cabling.)
Radio telemetry purchased from 3DR.
An unused 3DR PPM encoder.
A new Spektrum DX7s with an AR8000 receiver/satellite.

I’ve re-verified all connections and circuits with a Fluke multi-meter. All batteries are balanced and deliver appropriate voltages. I am unable to identify other, electrical or software issues. All methods for set up and operation are diligently adhered to, save for the mentioned arming work around that transiently worked.
Suggestions, questions or insights?

This is a battery failsafe operation… Goto Initial setup>mandatory>uncheck throttle failsafe box and make sure the “low battery” and “low capacity limits” are appropriately set for the packs you are using… Hope this helps…