I replaced the screen but no display

"Seems like a damaged replacement. as @benjamen50 said.

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"Did you unplug battery during the LCD change?

If not possible backlight filter damage."

"a lot of these spurious display's are not great quality and falsely grade them selves by letter for example grade A all the way down to grade F and they say this means they have been tested and checked if they are grade A to guaranty they work which is bull to say the least you get the same display's no mater what they are graded, Any of the spurious display is a lottery so you may have gotten a dead display just order another and try again.

also to be warned with spurious display's there is a very common issue with iPhone that use spurious parts where they will just boot loop after a update the reason for this is the iPhone dose a component check when it restarts after installing the new software and if it detects that the display is wrong (which happen's a lot) the phone is stuck on the boot loop as it detects issue with the part."

If the old screen is working, then the new screen is defective. With the new screen attached to the device, hold the phone under bright light (preferably the sun), tilt it on an angle against the light and you might see an image in the background. That means the back-light is out on the LCD. Even if you don't see any image, it's still a defective screen.