My phone switched off because of low battery and when I kept it for charging a black screen appeared. It is just blinking on and off. The same problem occurred previously also. I gave my battery to a technician for repair then battery worked, he said that he booted the battery. So how to boot when the battery is bad?
If you claim that you took it to a technician to repair it, are you sure the problem of your battery was solved? Have you considered replacing the battery with a new one? Or using another Samsung's battery on the phone?
Once you have a good battery you can know check for other issues that could be affecting your phone.