Dishwasher showing door locked/ nothing else

Just got a kenmore dishwasher from a family member whom said it worked perfect. Threw my old one away, plugged this one in and all it shows is the door is locked, and if i presss cancel/drain, they just start blinking!! Any help whatsoever would help, please.

First check to make sure the polarity of the electric hook-up is correct; and make sure the connections are secure.