Is it possible that the controller was the cause of the problem ?
Tell you why.... I followed Nintendo's instructions from their website which said unplug all controllers, remove cart, unplug for 30 seconds and try again and add devices as i go along.
Did that and it switched on. Added a game and switched on and it stayed on for like 1 hour with no problem. Added controller and after a few minutes it died.
Repeated with ANOTHER controller and i've been playing Goldeneye 007 so far for the last 1 hour without any problems whatsoever.