Оригинальный сообщение: pierrej ,
have your performed a PRAM and SMC reset? if not, try those. to reset the PRAM, press "command + option + P + R" on your keyboard during the post (before the chime) and wait for a second chime. the SMC might have already been reset if you went to an apple store, as it would be reset after 10 second of getting no power.