If your mobile phone is dropped into water, it can have various problems like it may not power on (we called as dead mobile), it may restart sometimes, in some cases it produce overheat while normal usage (although it is normal in some models!), its battery may drain and discharge in quick, it may hang and freeze frequently etc. those problems are effect of short-circuit in a mobile board.

Here you can learn how to check short in mobile phones also water lock removing methods.

If you ready to repair a water locked mobile phones, first you will have to remove its shorting.

Procedure to Removing Short in Mobile Phones:

1. Dismantle your phone using precision screw driver and get out the printed circuit board (PCB) of the mobile phone. Be careful while dismantling of phone, because some screws are very small, if you have not noticed, you have the probable chances to damage or bent the PCB board. After removing all screws you have to remove LCD, camera, etc. then you can get your mobile board out.

Note: in some cases you need a hot air blower for dismantling cases of mobile, because they are tightly glued.

2. Clean the entire PCB with any circuit cleaner like spirit, alcohol, thinner, IPA, etc.(I personally recommend IPA solution) Now dry it completely using hot air blower(SMD rework station). After each step, you have to check if shorting is gone or not. If not, proceed to the next step.

Note: You can check the short is presence or not in a Battery Connecting Terminal of the mobile board

3. Now try to deep clean the PCB. Here we are using a liquid called Elma or Alma.

Precautions to follow before Elma procedure: Make you sure are you removed the LCD display camera, etc. from the PCB before dipping the circuit in Elma. Also make sure, you have dried the PCB completely. It’s advisable to dry the PCB twice as water droplets remain below the chips on the motherboard.

Elma procedure: Dip the PCB in Elma solution for 2 to 4 hours. Remove the PCB and clean it with a brush. After that dry the PCB completely, this is very important because even a droplet of water or moisture is presence, short will not remove.

(For drying a PCB use SMD rework station)

Alternate method with Elma solution: You can also use an ultrasonic cleaner to do the above procedure. The advantage is that you do not have to wait for 2 to 4 hours. Instead you will finish the entire procedure in less than 15 minutes.

If shorting goes, you may think there was some dust particle, which lead to shorting. Always consider dust to be one of the worst enemy for a smoothly working circuit board. The other enemy is moisture. If the motherboard is in still short, you will have to follow the advanced procedure. Follow the step below:

There are two things we should consider:

1. A component (basically Capacitors) or IC on the PCB is short and making the entire PCB short.
2. The entire PCB is short

Manually inspect if any component like resistor, capacitor, diode, etc. is short. There are more chances of capacitors being short. They would look a little more dark or black in color because of getting burnt. Remove it and then check shorting with a multi meter. If it is gone, you have to solder a same, working component in its place. If still the problem is not solved, proceed further.

Connect the PCB to its battery, press the power button and keep it in this position for 10-20 seconds. Remove the battery and immediately check if any component or IC is heating. The part which is heating is most likely short. Remove it and check again. If the problem goes, replace the heating component / IC (you can do with this using DC power supply meter also, I personally recommend this method for effective result)

If still there is problem then it is quite difficult to repair. You will have to remove all the components one by one and check if shorting has gone or not. The part after removing which, the problem goes, is short.

If the IC is short you can reballing the IC, if you have BGA kit or BGA machine that is actually chip level work.

Note: The above procedure will be the same for all brands of cell phones and tablets including Samsung, iPhone, Nokia, Sony, HTC, LG, Motorola and Chinese handsets.