Original post by: iBroke ,
This issue sounds to me like you have accidentally popped the backlight fuse. This most typically happens with the iPad 4 and iPad Mini, and is caused by removing/reconnecting the digitizer and/or the LCD without first disconnecting the battery (notching a guitar pick and jamming it into the battery connection after removing the single screw is the easiest way to ensure the power is disconnected.) and creating a voltage surge in the logic board. This fuse is very fickle, and will pop very easily. Shining a bright LED flashlight on an angle at the LCD, should allow you to see the Apple logo, so you know it is indeed the backlight fuse. If you determine your issue to be the backlight fuse, you are going to have to either jump/bypass the fuse (not really recommended, but a fast fix), or replace it. There are many articles online with close up pictures to allow you to identify the faulty part.