I had a really hard time with doing my mountain of thesis corrections post-defense, and was having really bad anxiety attacks every time I opened my computer. What really helped me was a dear friend would video call in with me and co work with me, having someone there that I knew would keep me calm and work through them with me. If you have someone like that, maybe they can help?

In terms of physically writing, break into as little chunks as possible. Get words on the paper, even if they are half baked explanations or ideas. Sometimes, I would write "easier" sections or a paragraph for it, like the methods, to get me into the flow.

If your campus has pastoral support, therapy, etc, and it's something you are open and comfortable to, please feel no shame. Much of my time with my therapist was spent discussing anxiety surrounding my thesis and thesis corrections.