How to Diagnose Wireless that won't turn on? I just bought a new d2 Tablet, and it seems to be functioning normally, except that the Wi-Fi will not turn on.  I navigated to the settings screen and selected Wi-Fi, and dragged the Off button to On.  It stayed at On  and displayed the text "Turning Wi-Fi on..." for five seconds, after which it turned the button back to Off.  It has done this repeatedly.  I know I have good wireless signal b/c I'm using it to submit this question from my laptop. 

Is there some additional diagnostic I can do, or do I need to see about returning it as defective?
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.