A few things you probably know but might not. If you have a network cable connected, the WLAN light goes out because wifi is automatically disabled. A full reset is carried out by removing the power cable, pressing and holding the reset button, putting the power cable back in whilst still holding the reset button, and continuing to hold for at least 10 seconds. Then release the reset button and the server should reset it's self (full reset, all settings go back to factory defaults).

Failing that, it sounds like it might be faulty.