Why is my computer coming on but my screen is not

@dbg074 start off by connecting an external monitor and see if that comes on. If so, it is possible that your replacement screen is faulty, bad display cable, bad display connector or even just a bad backlight driver. A simple check for that would be to darken the room and turn the computer on. Then use a flashlight and angle the light at the screen on different areas. See if you can make out your desktop or even the computers splash screen etc. Let us know what you find out.