I wrote this answer in response to another mom’s post in one of my parenting groups. I thought it might be useful to others, so I’m sharing it here.
This mom is having trouble getting her child to comply with any directives at all, including school work, hygiene, meals, and bedtime. Here’s what I wrote:
I’m so sorry. I am having similar struggles with my kids. It is so, so hard. Unbelievably hard. I don’t know if any of this will work for you, but here are a few things that sometimes work in my house:
1. I’m not sure where you live, but most cities and counties have a mobile crisis unit that will send a mental health professional out to your house in case of emergency. Google to find one near you and save their number in your phone. If it ever gets to the point of a serious meltdown, violence, or self harm, don’t be afraid to call and ask for help.
2. Make a list of all the problems you are having with your child, and prioritize them. Pick just the most important 3 or 4 things to work on, and choose to let the rest go for now. There have to be some things on your list that are not a matter of life and death. (For example, can you choose not to enforce meal times or hair brushing?) We are experiencing an unprecedented, enormous catastrophe. It’s ok to just be getting by right now.
3. Forget about enforcing the structure. Just HAVE the structure and follow it yourself. Put a schedule on the wall that says when you will get up, do hygiene tasks, eat, work, etc. When it’s time to do something, just say, “it’s time for breakfast,” (or whatever) and then have breakfast. If your kid doesn’t participate, don’t worry about it.
4. Refuse to argue. If you tell your kid to do something and they whine back that they shouldn’t have to because XYZ, resist the urge to respond with your side of the argument. Just repeat that they have to do it. (You can give a reason one time, of course. Just don’t keep going back and forth.)
5. During a calm period, Ask your child for ideas on how to solve a particular problem. I know this sounds cliche, but sometimes they’ll give good suggestions. If they do, follow them.
6. If they start fighting about school work, let them be done for the day. It’s really not worth a fight.
7. When you give a consequence, choose something you won’t have to “police.” For example, you can take away screen time with parental controls instead of having to catch them watching screens and making them turn it off. Don’t let the punishment be one more thing to fight about.
8. Make sure to spend at least part of each day laughing with your child. You can just look at funny memes or tell a funny story about something they did when they were little. It’s more important to have a good, loving relationship than to get all the other stuff done. Plus, strengthening your relationship might make them more likely to listen to you.
I hope this helps. These are things that kinda sorta help in my family. They may or may not apply to yours. I’m sorry you’re going through this. 
Nicole Roder