My phone also fell (with the lower part) in the water. I had the same problems.
I renewed the digital LCD display and the USB charging board. My phone is fine again, only the micophone doesn't work anymore due to corrosion of the connector at the lower part on the flat cable. I am searching for a new cable.
I am trying to get an new cable but Lenovo won't help me, (they say I am not "qualified" to repair a phone ;-). ) so I am still looking for a new black flat cable. But the externe microphone with the earphones works well, so I saved my phone....
Perhaps you can do the same?