My Samsung galaxy S20ultra white display

My Samsung S20 Ultra's screen has turned white and is showing some unusual behavior. Occasionally, when I double-tap the screen, the background live wallpaper appears for less than 5 seconds before disappearing again. The screen is cracked, and touch functionality is partially working - I can answer calls, reject them, and switch off alarms, but only when the screen is white. Can anyone help me fix it without buying another Lcd please