Jerry said:
I am surprised it still works at all! It is possible that there is still
water or humidity on the circuit board, or even in the microphone. The
proper fix would be to replace the defective parts if necessary. There are
no so-called pots to adjust in these. The set-ups for most cell phones are
all done with interface softwares using dedicated calibration systems. You
should have mentioned the make and model.
Considering the low cost of these phones, they usually do not pay to
service, unless the fault is very minor. When signing for some types of
plans they even give away most of these models as part of the plan.
Since you have nothing to lose, I would try drying it out with low heat.
For example, if you live in a dry desert area, just put it outside in
the sun for a day. Or remove the battery, put the phone on a plate,
turn your oven to 200 degrees, put the plate in the middle rack, leave
the oven door open just a bit for air circulation, and let it "bake" for
several hours. If you can arrange a small fan (like a muffin fan) to
circulate the air around it, that will help. Or put a small bulb (25
watts) in a table lamp, and somehow balance or support the phone on the
shade above the bulb. Turn it over occasionally. The column of warm
air rising from the bulb will heat the phone and tend to suck out any
moisture.
Any source of modest heat should be as good as any other. Air
circulation (to carry away the moisture) is important. The process will
be faster if the air has low humidity.
Bill