This solution may help for hardware repair on Samsung I9305 Galaxy S3 with not working touch screen problem. If the touch screen digitizer is broken or cracked of your Samsung GT-I9305 Galaxy S III, you may only need to replaced it with a new touch screen glass digitizer. Just look for Samsung GT-I9305 disassembly guide to properly dismantle the phone.
The first step that should be done is to replace the touch screen first. Is the touch screen replacing solve the problem or not. If it does not resolve the issue try the next step.
The second step that should be done is to check whether there is a dirty touchscreen connector or corrosion, if indeed there are dirty or corrosive try to clean it, and then check the touchscreen connector lines like in the image below. Check the track one by one if there is a path-breaking try doing jumpers.
After dis assemble of Samsung GT-I9305 look at mother board and If you found some rust carbon or water damages then it can also be cause of Samsung I9305 Galaxy S III touchscreen problem to solve and fix touch screen problem in Samsung GT-I9305 Galaxy S3 clean all the rust and carbon with electronics cleaner and apply hot air to make it dry.
The solution above showed a Touch Accelerometer chip that used to sense orientation, detect direction in multi-access direction of the Touch Plate module. If the chip is damaged the touch screen will not work and remains unresponsive.
Samsung GT-I9305 Touch Problem Solution Not Working Repair Samsung I9305 Galaxy S III Touch Solution