New Display not working, water damage

My brothers iPhone 4s had a cracked screen so he asked me to replace it for him. I ordered a new display assembly and installed it. The new display showed a bunch of vertical lines in different colors. I got another new display and this one showed the same thing.

I asked my brother if the phone had gotten wet and he told me that it had actually fallen in the toilet before but worked afterwards. I proceeded to completely disassemble the phone down to the logic board. I cleaned the logic board with rubbing alcohol using a toothbrush, making sure to clean all the connectors very good. I dried it very well and used a can of compressed air to make sure there wasn't any moisture left. I then let it sit for about 30 minutes.

After this I out everything back together but yet the display showed the same thing, colored vertical lines. I doubt both new screens are bad. The backlight on both screens turn on.

I even tried a brand new battery thinking that just maybe it could help fixing the problem to no avail. What other parts can I replace? Only thing left to replace I think would be the dock connector.

Is this iPhone a paper weight now? Or could it somehow still have some life left in it?

Any suggestions would be appreciated.