Your issue might be one of several things that you can try and correct.
1.) screws over tightened. Let the phone battery charge to 100% before starting
2.) if the LCD needs to be Callibrated because of the order while you took parts off.
3) double check the LCD snap down connections , gently feel for the right spot to gently apply pressure to feel the snap then rub a plunger accross the top of the connector to ensure solid contact is made.
4.) the order in which you disconnect the battery matters , disconnect the battery before you disconnect the LCD connectors, and reconnect the LCD before the battery. Then once your finished putting everything back together without over tightening the screws( use lock tight) you need to use a USB cable and do a restore on a PC , that is the only way to get the LCD Callibrated , the software that calibrates the LCD isn't available when you do a WiFi restore.
you might have one off to the left or right a bit. First go back through all the screws especially the 6 screws that are located, "3 on each side, "of your digitizer that holds the silver plate on the back of the digitizer, loosen every screw you've tighten, and when you go to tighten the screws down, don't over tighten them, they are designed to only be tightened to the point that it stops turning. Over tighten screws can cause a whole barge of issues.
2.) finally, do a hard reset ( hold the home button, & the power button down together until the phone turns off, and a black screen with the white Apple logo shows up on the screen, then let off both buttons and let it reset.
See where those tips get you.