I tutor kids like this, too. There’s just this blank panic, like my question opened a drawer in their minds, but there's nothing inside but a tangled slinky and two broken pencils.
It is salvageable...in small groups stuffed with kids who are not like this, with friendly interactions enforced by the tutor. I have this one year 8 who got 14% in her unit test. I asked if she had read the unit. No, she hadn't. A nerdy year 6 opined she might try doing so next time. She did as he suggested and got 62% on the next test.
The thing is, it wasn't that she couldn't read or struggled to understand the text. She honestly didn't know that reading it would help her get good grades. And this is an elite British-curriculum international school, available only to parents who can afford to know better.
