I own a WW2.0 that still has the same Welcome message from the previous owner/named car wash! I keep trying to get around to changing it, too, so I've done some research.
The directions are in the manual. It requires you to expose the message board connector, connect a null modem cable, and use the terminal program on a laptop with Microsoft Windows and give it some commands including the new message. The directions in the manual seem straightforward enough. (A modern laptop probably doesn't have a serial port, so you'd need to buy a USB to serial null modem cable).
My distributor told me that he won't do them anymore, because he fried the sign and his laptop doing it for a customer. I'm not sure if this is even possible, but what he said happened. To be fair, crazier things have happened. And so he wants to send it out to get changed. That would be downtime, which is why I haven't done it yet. I since found the directions and haven't had the guts to do it myself on a rainy day.
