ust replaced the fan now powers up but black display... now what?

you laptop is not powering up properly. when you power up it directly goes to sleep mode or it's not passing the diagnostic mode. you can do is the remove all the jacks from the logic board and remove the battery also. just leave the magsafe inside and lcd cable with the logic board . remove the keyboard flex also. after removing all the flex from the logic board try to power up with charger in by jumping the power pads on the logic board . you will see these near the keyboard jack on the motherboard . these just above the keyboard jack . after connecting charger in jumpin these 2 pads with anything like pin etc. this will be help you. if it power up then slowly -2 put the jacks back to logic board one by one . means after powering up then shut it down then put one flex back on the logic board then power up . when you get the same problem with some thing that thing you have to change it or replace it.