Ford 500 trunk button doesn't work and no keyhole!

My grandma's 500 trunk button (near the steering wheel I think) doesn't work. When you push it it makes a click sound but the trunk won't open. And to complicate things there is no visible trunk keyhole? Maybe it's in "valet mode" if there is such a thing? There's no owners manual either. Help me help my grandma so she can fit groceries in the trunk!!!

Do you know what year her 500 is? You can view a PDF of the owner's manual here (https://www.fleet.ford.com/maintenance/owners_manuals/default.asp) which may give you some guidance.

-Rod