frazzle

I went to answer the phone and when I came back the eggs were burned to a frazzle.

我去接了电话，回来的时候鸡蛋全都煮焦了。

She's worn herself to a frazzle (= made herself very tired and nervous) trying to meet the deadline.

为了能如期完成，她把自己弄得筋疲力尽。