Hi all! I really need all of you to help!

This morning I started my X, the A/C control did not show anything, just dead at all. No response when I pressed the buttons. Meanwhile, it keeps blowing hot air into the car through vents in footwell, and the air was getting hotter after engine warmed. I turned off the car and got the key out, it was still blowing heat air. No way to stop it. What is the problem? Is it the A/C climate control dead or something else goes wrong? Right now, I could not stop the heat blowing, so I just cut the battery power.

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.