Samsung Galaxy Note 2 — Note2 Screen issue after outer glass replacement

Hii all

I have a Samsung Galaxy Note2.
I accidently broke its outer glass after dropping.

Few days back I replaced its outer glass which was ordered from ebay.

Issue is that after this replacement the screen has lost its resolution. The black color appears grey and the screen looks like a cheap vga display especially at lower brightness. However at maximum brightness it looks nearlly normal.

Is it because of
1. overheating the screen has experienced during the outer glass removal ?
2. due to cleaning with isopropyl alcohol which I used to remove the initially remanent glue on touch screen?
3. Due to dead pixels?

I tried using dead pixel removal app but it didn't work.
How can I bring the screen back to normal?