I recommend getting one signal to work properly through your isolated rail section.
Install the other at the other end later, then wire it to the isolated rails.
There should only be the two power wires to the computer board, plus the wire to the isolated rail, and the signal plug installed into the computer board.
The two power wires supply power for lighting the signal. The isolated rail tells the computer board to change the lights on the signal. The Signal Plug pulls power from the board and receives communications. The board has the automatic timing for changing the light sequence programmed into it.
No other wires should be connected to the board. Check that the power wires are going to the correct poles. The isolated rail is only one wire and needs the input of the power wires. I wish you luck. If one signal works, try the next. I did have one control board that did not work correctly. Try a different board on a signal that isn't working.
I just remember that the power wires can be daisy chained with a set of set screw clips for power input and a set for power output. It does not make sense that there would be a difference between the sets, but try switching the power wires to the other pair of input/outputs.
Check your signals by plugging them into a board you get to work. Then you will know your signals are good.
Swap the boards onto the signal that you get to work to verify that each computer board is good.
Good luck and best wishes. Have a good weekend.
Sincerely, John Rowlen