iPod touch 4G Screen Problem PLEASE HELP!

Please help! I have an iPod touch 4th gen. I attempted to replace the battery, (i guess apple likes bad batteries, as this was very difficult!), and of course I had to remove the screen to do this. I did the battery replacement, and as soon as I installed the screen again and powered it up, i immediately noticed that the screen is mostly white! It still registers touch, but there's very little contrast such that i can just barely see the app icons and text on the screen. Some icons like the battery charging logo are odd colours, almost like it's been inverted. But other screens like the settings menu are barely effected.

What i tried:

1) iTunes factory reset (didn't work).

2) display accommodation/ colour settings (made slight difference but still almost none).

What could have happened here? If anyone can help, please let me know. I attached pics here V