Help... I was getting a fan failure message, so I ordered a replacement fan. It came today and I replaced it. Now my laptop will not boot up at all. I put the old fan back in and when I start the computer, you can hear the fan kick on, but the system don't boot up.

Can anyone help me? Thanks

Make sure that you didnt disconnect anything importent like other ribbon cables. And make sure everything you unscrewed is properly grounded.