Dead spot on screen after replacement

I got my broken phone screen replaced today — it was a full LCD replacement — but an area of the screen is unresponsive to touch. It’s just a small section, about an inch tall, near the bottom of the screen, but I can’t even get into the phone because the dead spot covers some numbers on the pinpad. Other than that, the screen is perfect with no other trouble areas.

I went in and ensured that the connectors are secure, and I cleaned them with 100% isopropyl with no changes whatsoever. The guy who replaced it for me said that he might’ve gotten the back of the LCD dirty, near where the connectors and stuff are (?),when he was replacing it, but that he “cleaned it” — could that be the problem? Should I try and fix it or just get a whole new LCD again?

Thanks anyways!