If your 4K flat screen TV is looking purple or blue after a while, it most likely just needs the backlight replaced. The backlight is made up of LED strips that you can order online for cheap.
Link for my replacement: https://www.amazon.com/gp/product/B07...


Check ShopJimmy to find the replacement for your model tv:
https://www.shopjimmy.com/categories/...


My model was a Sharp 55" 4K
Sharp LC-55LB481U



The video I followed to replace the LED backlight:
   • Sharp TV LED Strip Replacement Help -...