He's completely beyond reasoning - don't waste your time.
Tips
memory
不 (not) + 可 (can) + 理 (reason) + 喻 (explain to) - cannot use reason to explain to them. They literally won't listen to logic.
mistakes
不可理喻 describes someone who refuses to listen to reason, not someone who is simply wrong. Don't confuse with 不可思议 (bùkěsīyì, unbelievable/inconceivable).
