just send to claim for warranty, if they ask just say "dunno oh" all of sudden cannot power on liao..hehe
i used to have a mainboard also struck by lightning, some more got burn mark. then i use a berus gigi gosok-gosok the burn mark area until the mark not tat visible...then send for warranty..and the technician without further asking me what's the problem directly assemble the mainboard with proc, ram etc..power up...Boom! again..he smile smile there and replace another new mainboard for me..heheh