In answer to your question, yes, it is fixable. But as @oldturkey03 pointed out your friend should stop using the device until it is properly fixed.
Water damage is fickle in that it can seem fine initially, but then give you some unexpected curveballs in the near future. For the best possible outcome and the longevity of the device you should clean it properly in an ispopropyl alcohol solution and clean any signs of corrosion, along with replacing the battery. The pink dot, depending on the location (like on the LCD), may not go away until/unless the screen is replaced. With these devices, that can get quite expensive.
To summarise:
# Stop using the device.
# Replace the battery
# Clean the logic board
# Replace the LCD
If you feel like this is out of your capabilities just take it to a local shop and ask them to do a repair on it!