Before you send it in, you might as well do the same glow plug test using the Glow Plug Power test in the Test Functions menu. Page 39 in the manual I have. Same thing, plug out, cap attached, plug touching case. If that fails, likely you have a blown power board, probably one of the FET's in the ECU (or at least whatever controls the FET for the glow plug). Why it would happen, I don't know.
To do a soft ECU reset, hold the Select Menu button down while powering on. Hold the button past Learn R/C, past Calibrate Temp until it does the reset. Probably 15-20 seconds total. Very unlikely this will accomplish anything to fix the problem.