Samsung S8 white bar - dull screen

[Benr87]

Hi, I think my S8 has bit the dust but just wanted some confirmation/suggestions. I dropped and cracked my screen (1 crack along the middle), it was working fine until it got a little warm.

Now I am presented with a bright white bar along the bottom, it covers the width on the phone but part of the home button is still visible height wise.

When I power up the device it works fine (just with a slightly annoying white bar) but when I lock the device and unlock again the screen goes very dull, I can read the screen but if I open an app I can't see it. If I lock and unlock multiple times it sometimes comes back to full brightness but the only real solution is to continually restart the phone.

Any ideas, if I get the screen replaced will this resolve or is it more of a fundamental fault?

Factory reset completed but to no prevail.

Thanks,