Looking at the specs from the website it looks as 10.8VDC is the lowest acceptable voltage the unit will stay powered up on. If you had been fighting the wind all day like most of us your voltage on the batter could have been floating just above this and with the in rush current of starting the trolling motor could have pulled it below that 10.8VDC just enough to cut the unit off. You could also remove the power plug out of the helix and use a voltmeter to measure the voltage at the plug and move the cable around to rule out a possible short in the power wire. Just a few thoughts.
