Heating problem

I have a 2000 bmw 323i and I had the radiator replaced because it was leaking. I got my car back and when I turn it on the air will only come on for the first 30 seconds and then just shut off and those controls won't work anymore. I'm not sure if radiator isn't pressurized correctly or that hvac control is broke. The light is also very dim on the controls when it first comes on.

New to bmw too, please help I don't want to take it to a dealer and get raped