How to configure SSL from ACM to subdomains?

Question

I have and EC2 set up to server both Backend and front end using nginx frontend.domain.org backend.domain.org

this is my nginx config file

server {
    listen 80;
    server_name backend.domian.org;

    location / {
        include proxy_params;
        proxy_pass http://unix:/home/ubuntu/Backend/app.sock;
    }

    location /static/ {
        alias /home/ubuntu/Backend/static/;
    }

    location /media/ {
        alias /home/ubuntu/Backend/media/;
    }
}

server {
    listen 443;
    server_name backend.domain.org;


    location / {
        include proxy_params;
        proxy_pass http://unix:/home/ubuntu/Backend/app.sock;
    }

    location /static/ {
        alias /home/ubuntu/Backend/static/;
    }

    location /media/ {
        alias /home/ubuntu/Backend/media/;
    }
}

now i created a load balancer and then a target group and added record in Route 53 to direct to load balancer but my target group is giving unhealthy what should i put after this / currently i set it to /

I tried changing / URLs but i didn't work also when i access it though load balancer DNS it gives 504error