Iphone 6 - LCD display weird colors flashing and cannot login at boot up

Hi,

my phone an iPhone 6 is showing a weird display of colors at startup towards the top of the screen. It lasts for several minutes until the color display dissapears and during that time the touchscreen is not responsive, i cant login. I am posting an image to show what it looks like. Does anyone have this issue with the same phone or a different model?

Do you know or think that replacing the screen will resolve? Apple quoted 300 to fix but did not say they knew for sure what it was, if it is just the screen, likely a third party could replace screen for 100-150 my guess. What do you think? Thanks