Touch screen problems after replacing LCD Assembly

I had a customer bring me an iPhone 5C with a cracked screen. I replaced the LCD Assembly which you know includes the LCD and the digitizer. A couple of days after giving it back to her, she started having issues with the touch not responding and by the 3rd or 4th day it quit working completely. I thought it might be the assembly I bought, so I returned the assembly and had them replace it. The next one did the same thing.

I got the assembly from Amazon. By Generic, sold by Select US and shipped by Amazon. I've always had very good luck with this combo, but things happen so I decided to try a different brand. It got good reviews. It doesn't work either.

I hooked the phone up to my computer and did a software update and reset it to factory but it still will not respond. Do you think all three assemblies are bad, or do you think there's a motherboard problem? I doubt it's a software issue because I reset it to factory.