Are you sure about not having a pin 15. I find two sets of instructions for new and old style boards resetting and both reference pin 15.
" Locate Pin 15 on 16 pin connector (P1). Pin 15 is
the empty socket to the right of the white/violet
wire on the top row"
If not how about disconnecting from power overnight then unhooking the batteries that should kill everything and allow time for any capacitors to bleed off then it should reset when you hook back up to 12V. Good luck and let us know if you get it going.
