Screen time for a 9year old

So I need tips on limiting screen time for my 9 year old. Since summer started Ive kinda let the whole screen time only on weekends rule and now my son plays all waking hours of the day. Only once we left for summer vacay did I realize we have a problem. He does not want to do anything else other than play his electronics, he literally sits in the basement and plays all day other than during meals. I need to restrict his time ASAP but not sure how to go about it without the meltdowns and tantrums.

Any advice would be greatly appreciated!