Constant amber power light on R6400 router

I bout the same model router from brick and mortar store. I'm trying to set up the wifi without a laptop connection and poor cell service so I needed this router to work with out a lot of fuss. Sat near cable guy as he did cable install. He said the amber light wouldn't turn white. He hooked his laptop into cable and could see modem was working (it's lit up). He said there was something wrong with router. After he left I got out instructions and tried set up. Still amber light. I returned the router to brick and mortar. I tried set up 5 times last night and still getting solid amber light. So since Netgear hasn't explained why I'm going to have to assume it's defective andy one I buy from Netgear will also be defective. I don't have time to go out to buy a new adapter. Shouldn't the adapter they put in the box work with their units?  If there's an answer to this proble post it quick because I'll be taking this one back for a full refund and buying another brand.