I took my working iphone 8 to the mall (fully working, just a cracked screen) and found a little kiosk that repairs phones. He took my phone to replace the screen and I paid. I came back later and he told me that "something went wrong" and told me that he tried multiple screens and the phone does not display anything. I was frustrated and furious, so I got my money back and told him to put my old screen back on. He did it, but once again the screen no longer worked!! The phone powers on, and I can receive phone calls but the screen simply won't work. My fear is that it's hardware damage that will cost a fortune to repair. What can it be?