We had this exact same issue Cliff. I bought that remote from LeBaron but they could not find the box or instructions for it. I ended up calling Motorguide and he told me this.
He said to unplug the trolling motor, but not just unplug, actually take away all power, ie: disconnect from the battery. Then connect back to the battery, plug back in the trolling motor and you have a 10 second window. Count to 3, then push the + and - together at the same time. He said it would do the long beep, but it did not, but it worked after that anyhow. I think the ticket was the disconnection from the battery that finally got it to work.
Good luck, hope it works for you.
Joey