ADDCO DH1000 Message Board Trailer Stuck on One Message

I have a 2006 ADDCO DH1000 message board trailer that I recently purchased. The trailer is in excellent condition all around with the exception that when I turn the power on and the current message operates properly, I am unable to get the keypad to respond with anything other than "PLEASE WAIT..." Therefore, I can't program any other messages to display on the board. I've called ADDCO a number of times and left messages requesting to purchase an operator's manual, but they have yet to...

ADDCO DH1000 Message Board Trailer Stuck on One Message

ADDCO DH1000 Message Board Trailer Stuck on One Message