Does the phone vibrate or give any signs of life when pressing power button or plugging in the charger? If yes, my guess would be either damaged display but if it truly "died" on it's own it's more likely poor connection between the display and motherboard, if you take the phone apart and press down on the display connector see if the display turns on.
If the screen turns on with pressure onto the connector the way to repair this would be to reflow the connectors and make sure all solder joints is solid. Requires experience in microsoldering which i assume you dont have so i would go to next step.
You could do some quick fix that most likely wont last for a long time by putting something between the connector and the plastic frame and then put the phone back together, so it always has more pressure onto the connector than usual.