Very Odd Issue With The 5C

So pretty much. I just replaced a 5c lock flex. When I put it back together I noticed a few weird things.

So the date and time wasn't right yet was connected to the network. I tried autocorrecting it via wifi but it wouldn't change. All the time the date and time wasn't right the home button didn't work, the proximity sensor didn't work and nor did the earpiece. The ambient light sensor did though. I connected it to iTunes to autocorrect the date and time and once that was done all three of the above worked again.

I've been working on phones as a business for a few years now so know a few things but this baffled me.

What was causing this issue?