The fine folks at i-Hacked tell you how to make an ADDCO portable sign say whatever you want. Not that you should because, of course, that would be wrong.
But dang, maybe ADDCO stands for Absurdly Dimbulb Design Creating Opportunity, because they sure make it easy
** HACKER TIPS ** Should [the control panel for the sign] ask you for a password. Try “DOTS”, the default password.
In all likelihood, the crew will not have changed it. However if they did, never fear. Hold “Control” and “Shift” and while holding, enter “DIPY”. This will reset the sign and reset the password to “DOTS” in the process. You’re in!