iPhone 5C digitizer doesn't work after replacement

I recently received an iPhone 5C from a friend with a broken screen (just the glass from first glance). I replaced the LCD and digitizer assembly with a new one and it shows vertical lines and a non responsive digitizer. I've tested the screen on other devices and it has worked fine. I've also tested other assemblies on the 5C and experienced the same issues. I've tried at least 10 times to make sure that the connection is properly seated, and it has been, but still haven't absolved the issues. I've inspected the logic board contacts with a 10x loupe as well as the smaller circuits under the protective covering and everything looks fine. The phone was dropped by the previous owner but the outer casing and original LCD assembly shows that it wasn't anything catastrophic; there's very minimal wear on the body itself. I very frequently make in depth repairs on all generation iPhones but this one has me perplexed. I've reviewed similar posts pertaining to these issues but none of the remedies have helped. Any insight is appreciated.