You should give us more details about the history of the device, the steps you took during the repair and the troubleshooting you did afterwards. The more info we have, the better the answer we can provide.

There are a few possibilities here:

• It could simply be a bad screen. Have you tried re-installing the original cracked screen?
• Did you isolate the battery before disconnecting (and reconnecting) the screen assembly?
• You may have accidentally damaged something during the repair. Re-check your work, closely inspect the connectors and surrounding area for any damage.