Touch Screen is Wonky After Replacing Charging Port

Subsequent to replacing the charging port circuit board on my S5, the display (i.e. digitizer, touch screen, etc) is not operating normally. The display illuminates correctly when the phone is powered up. However, it exhibits the following intermittent behaviors:

- unresponsive "dead" areas on left-side;

- "ghost" taps;

- apps windows quickly appear and disappear.

The phone will behave normally on some occasions.

I presumed a cable connection issue. I disassembled the phone, re-seated all connectors, re-assembled and powered up the phone--same problem.

I was extremely careful and very deliberate during the initial phone disassembly. I was just as careful and deliberate as I replaced the charging port circuit board. I was similarly careful and deliberate during reassembly of the phone. Based on these facts PLUS the intermittency of the phenomenon I described, I am not yet convinced I broke the digitizer assembly. It just seems like there is some simple "thing" I have missed.

Suggestions?