How can I change the display on my LaserJet 4000 printer from Demo to Ready?

I have two LJ-4000 printers. My first one always reads READY on the display after I turn it on as do all the other LJ-4000 printers I have used. I recently bought a used one for my other office and it always says DEMO after I turn it on. It works fine but I would like it to read READY. Is there a way to change that?