Samsung Galaxy S3 I9300 On Off power Button problem,
Samsung Galaxy GT-I9300 Power Switch button Key Not working.
This solution provides the connection line paths of the Samsung I9300 Power ON-OFF/END switch button key. This may help fix if the phone doesn’t tuns ON but it shows charging indication when the battery charger is plug-in.
Just refer to the solution below and locate the highlighted components where the said power on off key is being connected.
If the device shows charging indications when the battery charger is being plug-in but doesn’t Turns On when the power key is pressed. The problem may possibly lies on a faulty flex ribbon cable. Refer to the solution below for it shows the connection line paths of the Samsung Galaxy S3 power key, which can be useful to trace the line paths for easy troubleshooting or repair.
Make it clean with electronics cleaner and apply hot air with heat gun to make it dry.
Check power button and its tracks as shown in diagram above.
Apply jumpers if path is missing and you can not see value with meter.