Water damaged repair gone wrong?

Girlfriends iPhone4 A1349 met water damage when she forgot she had it in her bra when getting in the hot tub. I had no clue how to disassemble an iPhone, but we did the phone in a bag of rice thing for a few days.

Turned on the phone and it was constantly powering off and no response from the touch screen when "slide to unlock". No response from the power button, volume button or the home key. After light research on my girlfriends part someone said to change the battery.

I ordered from iFixit and changed the battery out along with the Liberation Kit. Still no luck with the screen. Then I came across the WHOLE DISASSEMBLE and alcohol cleaning process, everything put back together just fine. But now it won't even turn on.

Nothing was damaged in the process like the connector ribbons and or metal pins. There was plenty of corrosion on the connectors which cleaned up nicely. But the phone is just unresponsive completely now. I am at a loss of what to do next.

We already replaced the phone so it isn't a MUST FIX issue. It's just annoying that my attempts failed. So I took everything apart again, re-cleaned everything obsessively to keen detail. It turns on, and stays on now(unlike before when it would power off after a short random time) but the screen, volume buttons, home key and power key has no effect to anything. I've heard replacing the digitizer or something would work?