Here’s a full solution for a damaged Samsung GT-I8200 ON and OFF key problem. This problem may result to unable the device to turns on but it shows charging indication when the battery charger is being plug-in.
Samsung GT-I8200 not powering ON.
Phone doesn’t turn on and also heats up when even when power is OFF.
Phone turns OFF randomly at any point.
Phone turns Off when you access a particular application.
Charger might be faulty.
Battery might be faulty or water damaged.
Any of the components in that system might be faulty.
Soldering of battery on board connector might be out.
Power IC might be faulty.
Samsung GT-I8200 Dead Does Not Start Solution
Samsung GT-I8200 keys Power Jumper
Samsung GT-I8200 On Off Button Ways
If all the above methods fail to resolve your power problems then all you have to do is to gently heat your Power IC with the help of a heat blower, if it fails to perform then re-ball and re-fix the IC.
If heating or re-balling of Power IC doesn’t do any good to you then replace your Power IC, as there is nothing you can do besides all that.