@knownasreview so that means the LCD cable has been torn.
Either the screen needs replacing or it needs to be taken to a repair store where they can do microsoldering to reattach the cable to the LCD.
Given that the iPhone SE screens are not OLED, they are fairly cheap so replacing the whole screen would be the more economical option.
Do note that the home button must be transferred from the old screen to the new one for Touch ID to work.