mobile battery is not charged by phone?

MY MOBILE IS WATER DAMAGED BEFORE 1 YEAR AGO....

As service person told My phone mother board got problame Or any ICS has Fail.

But still Last 1 year i am using my mobile by external Battery charging ,,I have not face any problame.

But if i am go for repairing ,Service person told it may have chance so Mobile will be Totally dead.

But due to external charge i have face problame for daily uses..kindly give solution...

thank you..