Help replaced screen now it's not working

If the orginal screen was not damaged during removal, reinstall it and see if the iPhone boots correctly. If it does then it could be the replacement screen causing issues.

While the replacement screen is installed connect it to the computer with iTunes installed and see it is recognized. I’ve installed repacement screens, worked first time through. Then other repairs had to do it 4-5 times because the small connectors are not seated all the way down.

Another place to check is if the home button Touch ID flex cable is sitting all the way down in the screen. I’ve connected the flex cable, installed the small metal cover, reconnected the screen, turned on the phone, booted all the way up and yet the touch screen was lagging and not functioning correctly. Found that even though the screen appeared to be flush with the iPhone base, it was actually slightly crooked, which causes the screen to work inconsistently.

Important thing is to make sure iTunes recognizes the iPhone and all the data is intact.