Why does the replacement lcd sceen not fully work

Hi,

I bought a replacement screen off ebay for my cracked screen for iphone 5. I followed every step to install it correctly but here is the weird thing;

When the phone starts up, the display is grey / dark blue and flickers. when I play around with the screen when in auto lock mode, (tapping the screen alot with 3 fingers, unlocking and relocking the phone) I can somehow get the display to work 100% fine. But once the phone goes back to auto lock position, the screen again wont display correctly and I 'll need to play around with it again in order to get back the proper correct display. I know I can have the phone to never go into auto lock and that will leave the screen displaying correctly, but at the same time, that will drain the battery rather correctly. Any solutions/explanations to this problem? Thanks.