iPhone 7 screen suddenly unresponsive?

Hi,

I got my iPhone 7’s screen replaced a couple of months ago (although not directly from Apple) and it’s been fine until this evening. At first it started to pick up movements on the screen I wasn’t making, and then about half an hour later the screen turned unresponsive and started flickering, however I could still use Touch ID. I tried to turn it off using the power and volume buttons, but whilst doing this large black boxes containing the entirety of the width of the screen started appearing. By the time I had restarted the phone the screen was entirely black, with horizontal grey lines moving down the screen.

Any ideas as to what the issue could be? Is it likely to be to do with the screen replacement? And am I able to go into the Apple store and ask for help if I’ve had the screen replaced elsewhere in the past?

Thanks!