Water damage occurs when a device comes into contact with liquid. There are many misconceptions about what might fix Water damage devices.
The biggest misconception is that drying the device will fix any issues. In actual fact, the water isnt what causes problems when a device is water damaged. The actual cause of the damage is the impurities contained in the water, and the impurities the water drags deep into the device.
When you use rice, silica, cat litter, or heat to dry a water damaged device, you leave behind the impurities the water (or liquid) bought with it. This can cause immediate damage, or the damage might take months. You might one day loose your Wifi, the ability to get reception, or the phone might not turn on at all. Worst of all, you could loose all of your data, and your phone might become too costly to repair.
Remove the electricity. If the device has a removable battery (or you believe you know how to remove the battery), leave it out of the device. DO NOT connect a charger, and if the device is on, TURN IT OFF!
This will prevent the electricity from interacting with the impurities, and causing irrepairable, or expensive to repair damage. Then, most importantly, TAKE IT TO A PROFESSIONAL!
Soaking the internals of a device in alcohol doesnt really help at all. Not in the long term. If you have ever had a device "cleaned" and had it fail afterwards you will know what i mean.
Components have cavities in which impurities will get stuck, like underneath BGA chips, the sheilds that are soldered to the board. That means that even an expensive ultrasonic cleaner might not help remove the impurities.
The sheilds will need to be de-soldered, so the the components underneath can be properly cleaned, inspected, bad solder replaced, and the sheilds then soldered back on after the clean process. The technician will then perform tests on the device to see if there are any shorts, faulty components, or other issues.
ONLY THEN can the device be safely powered on. This process can, and DOES take extensive time (days, sometimes over a week). This is due to the level of work involved. If you have been told water damage can be fixed in half an hour, it just isnt being done properly.
If you remove the electricity from a device, and get it to a technician who can clean it properly, the time required to repair the device is often much less, and more often than not everything will function afterwards, without the need for costly board level repairs.
DONT BE FOOLED! If your device seems to be fully working, TURN IT OFF. It WILL fail. Maybe in minutes, maybe in months. Each situation is different. If you value your device, take it to someone who can clean it BEFORE it fails!
Ask your technician if he/she will at least do all these steps, after all you are entrusting him/her with your valuable device. if not, he/she is just not doing the job properly.
Not all water damage phones can be repaired or is economically repairable. If caught in time and you have followed the above advise theirs a good chance the phone will work again after the correct cleaning process without any further work.