You have a hardware problem indeed, and that's the new screen itself.
Either it came defective, and that's very common; or you damaged it during installation (it, or the cables connecting it to the board), and that's even more common.
To double check, put back the old screen and if the horizontal lines are gone like I think, the issue is with the new screen for sure.
Be careful not to pull on the screen when the cables are attached to the logic board. That's a sure way to damage them and cause such an issue. Also exerting force to seat a screen in a bent frame may damage that screen as well.