Per the advice of the clueless AT&T salesman, I took it to a wireless repair shop.
The guy had my phone less than 10 mins. He came back in, told me I was right (a connection had come loose) and told me "no charge". I told him I HAD to give him something, so he took $5.
I know some ways to save white screen, as blank screen.. ur,,, maybe can help
Instructions:
1. Turn off your iPhone with the Sleep/Wake button. Now it is completely powered off. Then you can turn on it again.
2. Press both the Home button and Sleep/Wake button, holding them for at least for 10 seconds. Then the battery symbol or the Apple logo will appear on your screen when iPhone is reset. If you see the battery symbol, please charge your iPhone until it is totally charged.
3. If the white screen is still there, go to connect your iPhone to the computer with the data cable.
4. Get in to iTunes and select your device from the Devices list.
5. Tap Summary and then tap Restore. Click Back Up if prompted.
6. Tap Restore to restore your iPhone.