It could be due to a few factors.
# The connection from the new screen to the board may not be fully connected. Maybe you need to press it in a bit more, until you hear a click or snap sound. Don’t force it, but try that first.
# Either the board port for the screen or the screen connector could be damaged. If it’s the board, then you will need to replace that, but to which at that point, you might as well just get another device if you prefer. If it’s the screen itself, see bellow.
# If the screen is not officially authorized by Huawei, such as getting from a third-party seller, that can cause a problem. If you did however, purchase it from Huawei directly, and you’re still within the window period of a return, then you could send it back for another one.
Any questions, please let me know.
Alex H.