New Member, need some help. Good battery, no start, no power.

Thanks for all your help guys. All connections and terminals were clean. Had it towed today to the ones who installed the new wiring harness. I am going to tell them to put new terminals on, remove the battery cut off switch, and remove the breaker. I just want the system simple. It has to be a ground. Going to leave the Demon grill on and live with it. I kinda like it. Will fill you in when I hear more from the mechanic. Thanks for the great welcome on the board and assistance. I am sure I will need more help from you all in the future.