iPhone not turning on nor connects to PC
So I got an iPhone 3g 8GB model, and I’m sort of an expert at fixing iPhones but not this kind. So I have this problem that the phone won’t turn on nor connect to my computer, but it does receive power when I connect it to an outlet with its original charger and brick. But the only thing that happens when I connect it to the power outlet, all it does is that it shows the apple logo and then 5 seconds later it dims the display but can still see the apple logo but with no backlit on the display. And also, when I click on the sleep/power button the apple logo comes back again and then does the dimming screen with apple logo again. So my predictions are that maybe the screen is okay, but maybe it can be the battery or the logic board that is bad. So what do you all think? Thanks!