《牛津》

a thing [singular] used with negatives to mean ‘anything’ in order to emphasize what you are saying

I haven't got a thing to wear!

She hasn't had a thing to eat all day.

There wasn't a thing we could do to help.

Ignore what he said—it doesn't mean a thing.

由此可知，否定句中的 a thing = anything, 但更为强调。

所以，你的句子翻译为“一窍不通”是正确的。