If your D-Link router has a continually flashing "Power" button, you may have run into a hardware problem with one of a few different causes. The hardware itself may be bad, you may have interrupted the router in the middle of a firmware update or the router could just need to be reset. The fix may be as simple as power cycling the router or as serious as replacing the hardware.
Disconnect the power cable from the D-Link router. Wait 30 seconds. Plug the power cable in and check to see if the power light is still flashing.
Check the physical connections on the D-Link router. Make sure the power supply cable is inserted correctly. Check the power supply cable for any physical damage that may cause a short or surge in the wire. If the power supply cable is physically damaged you need to contact D-Link for a replacement.
Determine the time that the D-Link router began flashing the lights. If you were in the middle of a firmware update and lost power, the D-Link router may have been "bricked." When this occurs, the hardware is unusable because the firmware code was not written correctly to the machine. You need to replace the router in this instance.