My Nokia 5230 doesn't respond to phone calls, text messages and alarm clocks.

I think it's a system problem. If your mobile phone is under warranty, I suggest you go to Nokia Customer Service Center for testing and play the system for free during the warranty period. If the warranty period expires, you have to pay the system fee. It is recommended to download the software from the internet, but there are certain risks in the process. Please consider all the pros and cons.

I hope my answer is helpful to you!