It sounds like your husband has checked everything he should; and yes it is very rare that LED Lights burn out.
The problem could be a bad light unit, bad wiring, etc. But since you say that your Motorhome is brand new; the problem should be fixed for free under your RV' Warranty.
Since it is covered under warranty, I would advise your husband not to start digging into the wiring system of the RV any further as he could very well void the warranty by attempting unauthorized repairs.
Hope this helps
Do you have any suggestions or comments on this topic? You can add them to this page by clicking on the "Click Here To Post Comments" link located near the bottom of this page.
Everything-About-RVing.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.