If you look closely at the lcd before you seal it up.... you can see images, but it will not illuminate the lcd. What needs to be done is simple, just power off the ipad (put into dfu, if necessary) and turn it back on and it will come back on with no issues. This is common in most apple devices. All that needs to be done is to find a way to reset. Now if the lcd still doesnt light, check the connections on the board for the lcd and make sure the clips for the connector are at the closed position, if its not closed, it will not make a good connection to the board. Also make sure that the flex cable on the lcd isn't torn. Last thing you want is a torn flex.... if that happens, you need a new lcd.
I highly recommend you do all this with the ipad before sealing it up.