Maybe your phone earlier was moisten or you made conccusion (by accident). If it was first case, try to put your phone into a sugar or salt (no kidding such things take out moisture, i have expierienced by myself with NOKIA 3110) if it was second case, try to repair it by yourself, of course if you know something about repairing mobiles. If you want some help, i will try to help you.
Good luck,
GSMdEvil |