In this case it seems more wise not to do it as I have just purchased my router and I can exchange it. I thought it is better to try fix it if there is any easy fix; but sure I don't want to lose warranty on it!
Thanks for the help.
Thanks TonyH for the reply.
I do have another AC adapter as I purchased two units of the router; one for home and one for office. The office router is working great, so I tried the adapter on the home router, but unfortunately it behave exactly the same; problem not resolved, and still can't...
I just got my brand new RT-AC66U, and unfortunately after the first day of using the router with no problems; my devices couldn't connect using wireless/wire connection, so I reboot the router, and I am stuck with the three lights of death!
I tried 30-30-30 reset, but even that wouldn't work...