"Solved:  my problem was the either the 3DR power module or the APM 2.6 input for the power module not sensing the battery voltage.  I went into Config/Tuning  and then Standard parameters and searched for BATT.   Then i Disabled the BATT_MONITOR…"

"Mine would arm up but only so long as the micro USB cable was connected.    Everything would work fine but the minute I pulled out the cable from the 2.6 then it would disarm. Thought is was maybe a voltage issue but not sure. I have the inputs…"