i just got an old 4.1 macbook 4.1 and put a new screen in it for a friend. after i got done installing it i turned it on got the white boot screen then the screen when black. i did hear the computer boot fully. i found out if i adjust the brightness all the way down then turn it back up the screens backlight works for a few seconds. i connected the laptop to my tv and mirrored the screens and works fine on the TV but not the internal screen. i took a flash light and can see the LCD working inside but just cant get the backlight to stay on. any ideas???