Ipad Air Not Turning On After Screen Replacement. Press and quickly release the Volume Down button. Enter password to get in this is a pain if you have password enabled if not go to next step 2.
After 8 seconds let go of the Power button. Alternatively perform a hard restart by pressing and holding both the HOME button AND the POWERSLEEPWAKE button until the Apple logo appears. Some computers might not provide enough power to charge your iPad or they might charge your iPad slowly.
The screen will go completely black you have entered DFU Mode.
Then press and hold the Power button until the device restarts. The screen shows the Apple Logo then goes blank -- Touchscreen not detected. If you removed a lot of tape to perform the repair make sure its put back you especially dont want to short the IC cable pins to the case. Now this is important press and hold down your Power button on the top of your iPad for 3 seconds.