do youj have any interior lights ?
And if you open the fresh food door on the right upper wall is the model number ,may I have it to better assist you?
ok in the fresh food ceiling you have the console ,
on the console you will see a 1/4 diameter hole just froward of the light and just behind the thermostat knob .
Take a straight screw driver or a butter knife and turn that wheel inside the holes your should be clock wise ,but if not try counter clock wise.
turn is just a few clicks and see if the unit comes on ?
I`ll hold on .
ok so that is the timer assembly ,which means it was stuck in defrost .
You will need tp replace it .
Here is the link for the part.
it is just held into place with two screws and four wire ,just swap the wires one ata time on same terminals.