How to Diagnose Wireless that won't turn on?
This is what i would do myself, and in that order :


Modify the way you authenticate to the Wifi access point. Removing temporarily any kind of encryption. If this fix your problem ---> Your phone most likely doesn't handle some advanced kind of WPA2 or something like that.
Look for an issue in the configuration of the access point itself. Look for MAC address filtering for example.
Finally as a last resort, use command line tools like "adb debug on your phone to read what's happening to your wireless driver on the phone.