The LCD would need to be replaced but usually these don't go bad by itself, I've had cases where liquid damage has caused this on the screen.
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I recommend that you take it to a mobile phone repair shop or something similar for a quote as a repair like this isn't always the best idea to do it yourself.
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I recommend that you take it to a mobile phone repair shop or something similar for a quote as a repair like this isn't always the best idea to do it yourself (LCD may need to be replaced and if the glass cracks digitizer as well).
The LCD would need to be replaced but usually these don't go bad by itself, I've had cases where liquid damage has caused this on the screen.
I recommend that you take it to a mobile phone repair shop or something similar for a quote as a repair like this isn't always the best idea to do it yourself.