What is your problem and correct the model #

Pull out the fridg and remove the screws from the metal motherboard cover.
Locate the 3 pin, gray power connector and remove it. Put a wire jumper between the mating pins labled line and def. Plug fridg in. If it goes in defrost, you have a bad motherboard, if not, probably either a bad defrost heater, or a bad defrost thermostat clipped to the top of the evaporator, a round metallic thing. I would replace both. Order them on this site.

Finally had a chance to look at the fridge and it was just as you said and the jumper did indeed turn on the heater element, thank you for that. So the supposition was a bad board. There was however a mysterious and suspect cut white wire going to a white multi-pin connecter at the top right of the board(maybe a dozen sockets (not all used)). the cut wire split out from a lump in the line (line filter?) along with another white wire still intact. I figured I was on the hook for a new board any way so I soldered it back together and plugged it in... no blue smoke. Any idea what it was or if perhaps this was part of the nonfunctioning defrost system? A timer relay maybe?

up date: replaced the board and 10 days later it Iced over again! I used the jumper trick to manually check the heating element and circuit was still working ran it for 20 min and restarted the fridge ice dam gone. So I don't have to manually defrost but still tedious every week to 10 days to pull out the fridge and such. Also the ice maker is not working. iced over supply? (though I don't think it has since the new board, and this was not previously a problem and we are a family of smoothie makers). Ideas anyone? 11/13 ...And again so now with it raining here the humidity is up and I have to defrost every 3-4 days and still no ice in the icemaker. Is there a way to test either the old board to see if the one I got is bad or is there an other component to test... defrost thermostat maybe? can this be tested without cutting the wires?