钻牛犄角 to get bogged down in details
Explanation
比喻思想方法狭隘，或固执地纠缠于细枝末节，不肯变通。
It means that the way of thinking is narrow or one stubbornly clings to small details and is unwilling to compromise.
Origin Story
从前，有个秀才，一心想考取功名，但他读书方法死板，只会死记硬背，遇到难题就钻牛犄角，不肯变通。他日夜苦读，却屡试不第。一次，他看到一个老农在田里耕作，便上前请教：“老丈，您看我该如何才能考取功名？”老农指着田里的一棵歪脖子树说：“你看这树，虽然长得歪七扭八，但它也结出了果实。读书也是如此，要灵活变通，不要只盯着一个死理不放。 ”秀才听了老农的话，豁然开朗，开始改变学习方法，最终金榜题名。
Once upon a time, there was a scholar who desperately wanted to pass the imperial examination. However, his study methods were rigid, only memorizing and reciting by rote, and when he encountered difficulties, he would stick to his guns and refuse to change his approach. He studied day and night, yet failed time and again. One day, he saw an old farmer working in the field. He stepped forward to ask for advice: "Old man, how can I pass the exam?" The farmer pointed to a crooked tree in the field, saying: "Look at this tree, although it grows crookedly, it still bears fruit. It's the same with studying; you must be flexible and not just focus on one rigid principle." The scholar was enlightened and changed his learning methods, eventually achieving success in the examination.
Usage
用作谓语、定语、宾语；形容人思想方法狭窄，不灵活。
Used as predicate, attributive, and object; describes a person with a narrow, inflexible way of thinking.
Examples
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他总是钻牛角尖，看不清事情的本质。
tā zǒngshì zuān niújiǎojiān, kàn bu qīng shìqíng de běnzhì.
He always gets bogged down in details, failing to see the essence of things.
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不要钻牛犄角，换个思路试试。
bú yào zuān niú jī jiǎo, huàn ge sīlù shìshi
Don't get bogged down in minutiae; try a different approach.