Rúguǒ nǐ zài zhèyàng zhí mí bù wù, jiù méi rén néng bāng nǐ le.
If you keep stubbornly refusing to see reason, no one will be able to help you.
Tips
history
Found in 《梁书·武帝纪》 (Tang compilation by Yao Silian): '若执迷不悟,距逆王师,大军一临,刑兹罔郝' — originally warning rebels against persisting in defiance of imperial forces.
usage
Strongly negative and impatient in tone — used after repeated warnings have failed. Often follows 劝/警告/教训…还是 structures. The implicit request is 'wake up and change direction.'