Simple solution to this problem, pal: Turn OFF THE TV and unplug it. Hide the remotes in a location accessible ONLY to you. Cancel your internet service. And GET YOUR SON OUT OF THE HOUSE during the day. At his age, he needs to be outside and playing with other kids as much as possible during the summer months. Sign him up for day camp or for Little League. Take him to the local parks and do nature walks and scavenger hunts with him. Call your local YMCA and find out if they have swimming and other sports programs which he can participate in. Take your son on trips to places like museums and amusement parks. In short, you can do just about anything with him, except allow him to be on the computer or play video games, or watch TV all day.
If your son has a TV in his room ( and HE SHOULDN'T, not at HIS AGE) then get rid of it. Ditto for a computer. He needs to have his computer time restricted ONLY to school work and school related activities, and YOU NEED TO BE A PARENT and MONITOR WHAT HE DOES while he's on the computer. That you haven't up to now is one of the reasons WHY your son is in this situation. It's UNNATURAL and UNHEALTHY, not only for him, but for YOU, TOO. Put your computer in a CENTRAL LOCATION where it can be monitored, such as in the kitchen, for example, or in your den if you have one. And then make it clear to your son that he's not ALLOWED to use the computer for anything other than SCHOOL WORK. No MORE YT, no more video games, period. Not until he's in HIGH SCHOOL- and even then, you need to pay close attention to what he does while he's online.
Lastly, don't give IN to his whining. He's testing you, and you need to put your foot down and make it clear that he's not going to get his way. He's not too young to start learning that the world doesn't owe him a living. One of the biggest problems with kids today is that they ALL have this sense of entitlement. They think that the world exists to serve them and life is all about getting what they want. Then, when they finally get out in the real world and are expected to work for a living, most of them CAN'T, because they have no idea HOW to do this. By letting your son get away with this nonsense he's spouting, you're CONTRIBUTING to this problem. Don't be an enabler. BE A PARENT. Your son needs that right now more than anything. He needs you to be a PARENT first, and his best buddy second. Yeah, I know it's tough, but you'll both be much better off if you don't cave in to him.