On my previous Norcold, I was able to use the light. On our new one I don't remember why but I know I couldn't do it. Maybe there was no power available easily.
I went down the drain tube, like others have said. Don't worry, they don't drain that much. Pinch the wire where it gets stopped and see how far you are making it. It seems to me I had to do that, and when I went outside I was nearly at the end of the tube
Don't give up, adding the inside fans makes our Norcold work as good as our home fridge. I had tried the little battery operated fans inside, and it is not even close to the same results.
Added, by pinch the wire, I meant hold onto it where it stops, so you can see how far you are getting it down.
2000 F-250 7.3 Powerstroke
2018 Arctic Fox 27-5L