Bought two replacement modules, just in case
The lights are in series and probably have some design defect/manufacturing defect. This is the second time in 5 years that I have had to do this. LED lights in a low-use setting like a refrigerator should last forever.
I changed the first unlit module; still not working.
I changed the second module; they all work now.
The part is expensive for what you get, a very unreliable product made in roc.
I'll probably be using the extra module I bought next year.