Chosen Solution
I bought a cheaper iphone8 plus with shattered screen . I was hoping to fix the screen and start using it. I replaced the broken screen with the new one. When I turned on the phone, the bottom left of the screen turned greyish/black. I thought that it must have been the circuit problem. I uninstalled the screen and reinstalled it but it still the same. Old screen didn’t have that issue. What could be the problem. Please help. Thanks
Do you still have the old screen at hands? connect the old cracked one again and see if that has the same problem. If the old one works fine you simply got a bad display from your supplier, unless you damaged it during the repair.