Liquid damaged - only original screen works

Hi, got an iPhone 7 Plus bought from someone. It came with a cracked screen, powered on but the touchscreen didn’t work. When opened, it came that there was a liquid in a few places so I took it into the bath and cleaned everything.

Phone still powers on, I’ve managed to restore it with iTunes but there’s no display or backlight. Tried with a few different screens and checked them on the other 7 Plus - all ok

The only thing is that when I’m plugging in the original screen - phone powers on as before - going to the starting screen with no issues but without the touch (original fault).

Any ideas what can be done here?

I’m happy to provide any more pics if needed.

Thanks