Screen Flickering After Water Damage

A few weeks ago my wife dropped her iphone 6 into the toilet (don't ask). The phone apparently would not immediately turn off and I am assuming eventually turned off when the battery ran down. I attempted to dry out the phone using rice etc. to no avail.

I decided to take it into a repair shop where they disassembled the phone and dried out the components using a solution I presume. After this, they claimed that the only issue was the screen needed to be replaced. After they replaced the screen they told me that the touch ID & rear camera didn't work. I had them put the old screen back on, and thought i'd do the screen replacement myself.

After I replaced the screen, they were correct in that the rear camera and the touch ID doesn't work. However the screen flickers off and on and horizontal lines appear randomly. I am guessing this is an issue with the flex cable or connector? With the battery disconnected and the unit hooked up to only the lightning cable, the issue is still there.

Any ideas on how I can salvage this phone or should I give up?