I seem to have a short somewhere in my boat. The cranking battery runs down when not in use over 2-3 days. all my electronic and pumps and everything else except my trolling motor is connected to it. I have determined that is the electronics by testing the fuses with a test light. All the electronics are connected to a fused circiut board under the dash. How do i test the board? any ideas? When the electronics are unconnected it still shows a short with a test light at the fuse block.