What is an appropriate punishment/response to a child not doing their schoolwork? Am I overreacting?

My son is 7 years old and in the first grade. If you read my post history, I briefly outlined some of my issues I have been having with him behavior wise, but those were almost always at home.

Now, schoolwork has always come easy to him. He has been doing his homework on his own now for the past several months with no problems. Lately, it's been like pulling teeth to get him to start his homework. When he comes home from school, he will get a snack, turn on the TV and plop himself on the couch with the TV on and his Switch in his hand. Since he gets home from school around 4, and he gets ready for karate around 5, I usually let him, so he has a little time to unwind after being in school all day. After we get home from karate, it'll usually be around 6:45-7:00. I will ask that he starts doing his homework while I get started with dinner. And he'll say "Okay, I'll start right now." But nope, its back to the TV and Switch. While I'm cooking, I'll keep warning him that he better be getting his homework done. Sometimes he does, sometimes he'll keep ignoring me and play with the electronics until I start yelling, and then with a lot of attitude, he'll get it done. Yesterday was no different. For some reason, even though we have several desks and tables available, he absolutely REFUSES to use them. He insists on doing his homework in the dark, on the floor or on the couch. He always tries to keep the TV on when he's doing it, and argues with me when I turn it off.

Last night I asked him about a million times if all his homework was done, and he told me yes. We had plans with my friend today to go to the movies to see Aladdin, since Tuesdays are the only weekdays that he doesn't have karate.

Welllllll, I just got an email from his teacher. Apparently, he was assigned some sort of project last week that was due today, and he did not hand it in, or even mention it to me. His teacher said that he was given several reminders that it was due today. He never told me anything about it. Yesterday was another one of those days where I have to nag the hell out of him to start his homework. (It took him 20 minutes just to "find a pencil") The only way he would do it was to work on it on my bed.

Now, for a little background: I have a 13 and a 15 year old brothers that we live with. They are famous for doing stuff like this, it's almost routine. They will slack off in school, not do homework or projects, my mom will come home and they get into a big fight about it, they get video games taken away until the project/homework is done, then everything is forgotten about for another month or two until the cycle continues. It's been the same routine for YEARS, probably since they were in elementary school.

So now that my son, who always excelled in school, is pulling this shit, my blood is boiling. He has been copying a lot of my teenage brother's bad habits lately, but never like this. This is the first time he ever messed up with his schoolwork like this, and I do not want it to become a pattern like it does with my younger brothers. This cannot be a habit.

As of right now, I promised the teacher that the assignment will be completed and handed in tomorrow for partial credit. The movie plans are cancelled, and all electronics are taken away (including the TV, which I usually don't take away.) They will be taken away until the weekend.

I don't know if this is an appropriate punishment, or if I am being too harsh and taking out my annoyance on my brothers on him. I highly suspect he has ADHD (I finally, after MONTHS of arguing, got an evaluation appointment set up for him for this Friday.) He always lashes out when he is "bored" so him having no electronics for a week is going to be hell for everyone. He has no actual toys, because he never wants them, he is not the type that enjoys sit down imaginative play like action figures. (We just donated a crap ton of toy robots and dinosaurs and Power Rangers last weekend) He has about 100000000000 Nerf guns, but no one to play them with, so they just sit on the shelf we built for them.

I want to make sure he never pulls a stunt like this again, but if I take everything electronic away, he will literally just sit and stare at a wall for a week. But the electronics are the main reason why he didn't do his project.

So, Parents of Reddit, what do you think?